feat(docs): add JavaScript introduction components and content

This commit is contained in:
sanbuphy
2026-02-15 16:23:15 +08:00
parent 4732d48777
commit 9c1a395962
9 changed files with 5243 additions and 2 deletions
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<template>
<div class="closure-demo">
<div class="demo-header">
<span class="icon">🎁</span>
<span class="title">函数与闭包</span>
<span class="subtitle">理解作用域链和闭包机制</span>
</div>
<div class="intro-text">
想象你有个<span class="highlight">背包</span>函数每次出门时都会把当时看到的
<span class="highlight">风景</span>外部变量装进去
<span class="highlight">闭包</span>就是这个背包即使离开了那个地方你依然能拿出当时装的风景
</div>
<div class="demo-tabs">
<button
v-for="tab in tabs"
:key="tab.id"
@click="activeTab = tab.id"
class="tab-btn"
:class="{ active: activeTab === tab.id }"
>
{{ tab.label }}
</button>
</div>
<!-- 函数基础 -->
<div v-if="activeTab === 'basic'" class="tab-content">
<div class="function-showcase">
<div class="code-panel">
<div class="code-title">函数声明方式</div>
<div class="code-block">
<div class="code-line comment">// 1. 函数声明</div>
<div class="code-line">function greet(name) {</div>
<div class="code-line indent">return "Hello " + name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line comment">// 2. 函数表达式</div>
<div class="code-line">const greet = function(name) {</div>
<div class="code-line indent">return "Hello " + name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line comment">// 3. 箭头函数 (ES6)</div>
<div class="code-line">const greet = (name) => {</div>
<div class="code-line indent">return "Hello " + name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line comment">// 简化版(单行可省略 return</div>
<div class="code-line">const greet = name => "Hello " + name</div>
</div>
</div>
<div class="playground">
<div class="playground-title">试试调用函数</div>
<div class="input-group">
<input v-model="functionName" placeholder="输入你的名字" />
<button @click="callFunction">调用</button>
</div>
<div class="output">
<span v-if="functionResult" class="result">{{ functionResult }}</span>
<span v-else class="placeholder">点击"调用"按钮看结果...</span>
</div>
</div>
</div>
</div>
<!-- 闭包演示 -->
<div v-else-if="activeTab === 'closure'" class="tab-content">
<div class="closure-visual">
<div class="scenario-selector">
<button @click="closureScenario = 'counter'" :class="{ active: closureScenario === 'counter' }">
计数器
</button>
<button @click="closureScenario = 'config'" :class="{ active: closureScenario === 'config' }">
配置器
</button>
</div>
<div v-if="closureScenario === 'counter'" class="counter-demo">
<div class="code-panel small">
<div class="code-line">function createCounter() {</div>
<div class="code-line indent">let count = 0 <span class="comment">// 私有变量</span></div>
<div class="code-line indent">return function() {</div>
<div class="code-line indent indent">count++</div>
<div class="code-line indent indent">return count</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">const counter = createCounter()</div>
</div>
<div class="closure-animation">
<div class="closure-box">
<div class="box-title">闭包环境</div>
<div class="closure-var">
<span class="var-label">count = </span>
<span class="var-value">{{ counterValue }}</span>
</div>
</div>
<div class="controls-area">
<button @click="incrementCounter" class="action-btn primary">
调用 counter()
</button>
</div>
<div class="explanation">
<p><strong>发生了什么</strong></p>
<ul>
<li><code>createCounter()</code> 执行后局部变量 <code>count</code> 本该消失</li>
<li>但返回的函数"记住"了这个变量形成了闭包</li>
<li>每次调用 <code>counter()</code> 都在访问同一个 <code>count</code></li>
<li>外部无法直接访问 <code>count</code>实现了数据私有化</li>
</ul>
</div>
</div>
</div>
<div v-else class="config-demo">
<div class="code-panel small">
<div class="code-line">function makeMultiplier(times) {</div>
<div class="code-line indent">return function(n) {</div>
<div class="code-line indent indent">return n * times</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">const double = makeMultiplier(2)</div>
<div class="code-line">const triple = makeMultiplier(3)</div>
</div>
<div class="multiplier-playground">
<div class="function-list">
<div class="func-item" @click="activeMultiplier = 'double'" :class="{ active: activeMultiplier === 'double' }">
<div class="func-name">double = makeMultiplier(2)</div>
<div class="func-desc">闭包捕获 times = 2</div>
</div>
<div class="func-item" @click="activeMultiplier = 'triple'" :class="{ active: activeMultiplier === 'triple' }">
<div class="func-name">triple = makeMultiplier(3)</div>
<div class="func-desc">闭包捕获 times = 3</div>
</div>
</div>
<div class="multiplier-input">
<input v-model.number="multiplyNumber" type="number" placeholder="输入数字" />
<button @click="doMultiply">计算</button>
</div>
<div v-if="multiplyResult" class="multiply-result">
<span class="result-equation">{{ multiplyResult }}</span>
</div>
</div>
</div>
</div>
</div>
<!-- 作用域链 -->
<div v-else class="tab-content">
<div class="scope-chain-demo">
<div class="nested-visual">
<div class="scope-level global">
<div class="level-title">全局作用域</div>
<div class="level-vars">
<span class="var-tag">globalVar = "全局"</span>
</div>
<div class="scope-level outer">
<div class="level-title">外层函数作用域</div>
<div class="level-vars">
<span class="var-tag">outerVar = "外层"</span>
</div>
<div class="scope-level inner">
<div class="level-title">内层函数作用域</div>
<div class="level-vars">
<span class="var-tag">innerVar = "内层"</span>
</div>
</div>
</div>
</div>
</div>
<div class="lookup-demo">
<div class="lookup-title">🔍 变量查找过程作用域链</div>
<div class="lookup-steps">
<div class="lookup-step" v-for="(step, i) in lookupSteps" :key="i">
<div class="step-num">{{ i + 1 }}</div>
<div class="step-content">{{ step }}</div>
</div>
</div>
<div class="lookup-rule">
<strong>查找规则</strong>
从当前作用域开始逐层向外查找直到全局作用域找不到则报错 ReferenceError
</div>
</div>
</div>
</div>
<div class="info-box">
<span class="icon">💡</span>
<strong>核心思想</strong>
<span v-if="activeTab === 'basic'">函数是 JavaScript 中的一等公民可以赋值给变量作为参数传递作为返回值箭头函数更简洁且不绑定自己的 this</span>
<span v-else-if="activeTab === 'closure'">闭包是函数和声明该函数的词法环境的组合它让函数可以访问外部作用域的变量即使外部函数已经执行完毕闭包常用于数据私有化函数工厂模块化等场景</span>
<span v-else>作用域链是 JavaScript 查找变量的机制当访问一个变量时引擎会先在当前作用域查找找不到就去外层作用域找直到全局作用域这种机制让内层函数可以访问外层变量形成了闭包的基础</span>
</div>
</div>
</template>
<script setup>
import { ref, computed } from 'vue'
const activeTab = ref('basic')
const functionName = ref('')
const functionResult = ref('')
const counterValue = ref(0)
const closureScenario = ref('counter')
const activeMultiplier = ref('double')
const multiplyNumber = ref(null)
const multiplyResult = ref('')
const tabs = [
{ id: 'basic', label: '函数基础' },
{ id: 'closure', label: '闭包' },
{ id: 'scope', label: '作用域链' }
]
const lookupSteps = ref([
'内层函数访问 innerVar → 在当前作用域找到 ✓',
'内层函数访问 outerVar → 当前找不到,向外层查找 ✓',
'内层函数访问 globalVar → 继续向外,在全局作用域找到 ✓',
'内层函数访问 unknownVar → 所有作用域都找不到 ✗ ReferenceError'
])
const callFunction = () => {
if (functionName.value.trim()) {
functionResult.value = `Hello ${functionName.value}`
}
}
const incrementCounter = () => {
counterValue.value++
}
const doMultiply = () => {
if (multiplyNumber.value !== null) {
const times = activeMultiplier.value === 'double' ? 2 : 3
multiplyResult.value = `${multiplyNumber.value} × ${times} = ${multiplyNumber.value * times}`
}
}
</script>
<style scoped>
.closure-demo {
border: 1px solid var(--vp-c-divider);
border-radius: 8px;
background: var(--vp-c-bg-soft);
padding: 1rem;
}
.demo-header {
display: flex;
align-items: center;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.demo-header .icon { font-size: 1.25rem; }
.demo-header .title { font-weight: bold; font-size: 1rem; }
.demo-header .subtitle { color: var(--vp-c-text-2); font-size: 0.85rem; margin-left: 0.5rem; }
.intro-text {
font-size: 0.9rem;
line-height: 1.6;
margin-bottom: 1rem;
color: var(--vp-c-text-1);
}
.highlight {
background: var(--vp-c-brand-soft);
color: var(--vp-c-brand);
padding: 0.1rem 0.3rem;
border-radius: 4px;
font-weight: 500;
}
.demo-tabs {
display: flex;
gap: 0.5rem;
margin-bottom: 1rem;
border-bottom: 1px solid var(--vp-c-divider);
padding-bottom: 0.5rem;
}
.tab-btn {
background: transparent;
border: none;
padding: 0.5rem 1rem;
cursor: pointer;
color: var(--vp-c-text-2);
font-size: 0.9rem;
border-radius: 6px;
transition: all 0.2s;
}
.tab-btn:hover {
background: var(--vp-c-bg-soft);
}
.tab-btn.active {
background: var(--vp-c-brand);
color: white;
}
.tab-content {
min-height: 380px;
}
.function-showcase {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
}
.code-panel {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.8rem;
color: #d4d4d4;
}
.code-panel.small {
font-size: 0.75rem;
padding: 0.5rem;
}
.code-title {
color: #888;
font-size: 0.7rem;
margin-bottom: 0.5rem;
text-transform: uppercase;
}
.code-line {
padding: 0.1rem 0;
line-height: 1.4;
}
.code-line.indent {
padding-left: 1.5rem;
}
.code-line.indent.indent {
padding-left: 3rem;
}
.code-line .comment {
color: #6a9955;
}
.code-line :deep(code) {
background: #333;
padding: 0.1rem 0.3rem;
border-radius: 3px;
}
.playground {
background: var(--vp-c-bg);
border-radius: 6px;
padding: 1rem;
display: flex;
flex-direction: column;
gap: 0.75rem;
}
.playground-title {
font-weight: 600;
color: var(--vp-c-text-1);
font-size: 0.9rem;
}
.input-group {
display: flex;
gap: 0.5rem;
}
.input-group input {
flex: 1;
padding: 0.5rem;
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
background: var(--vp-c-bg-soft);
color: var(--vp-c-text-1);
}
.input-group button {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.5rem 1rem;
border-radius: 6px;
cursor: pointer;
}
.output {
background: var(--vp-c-bg-soft);
border-radius: 6px;
padding: 0.75rem;
min-height: 2.5rem;
display: flex;
align-items: center;
}
.output .result {
color: var(--vp-c-brand);
font-weight: 600;
font-size: 1.1rem;
}
.output .placeholder {
color: var(--vp-c-text-3);
font-size: 0.85rem;
}
.scenario-selector {
display: flex;
gap: 0.5rem;
margin-bottom: 1rem;
}
.scenario-selector button {
flex: 1;
padding: 0.5rem;
background: var(--vp-c-bg);
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
cursor: pointer;
color: var(--vp-c-text-2);
transition: all 0.2s;
}
.scenario-selector button:hover {
border-color: var(--vp-c-brand);
}
.scenario-selector button.active {
background: var(--vp-c-brand);
color: white;
border-color: var(--vp-c-brand);
}
.closure-visual {
display: flex;
flex-direction: column;
gap: 1rem;
}
.counter-demo {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
}
.closure-animation {
display: flex;
flex-direction: column;
gap: 0.75rem;
}
.closure-box {
background: var(--vp-c-brand-soft);
border: 2px solid var(--vp-c-brand);
border-radius: 8px;
padding: 1rem;
text-align: center;
}
.box-title {
font-weight: 600;
color: var(--vp-c-brand);
margin-bottom: 0.5rem;
}
.closure-var {
font-size: 1.5rem;
font-weight: bold;
}
.var-label {
color: var(--vp-c-text-2);
}
.var-value {
color: var(--vp-c-brand);
font-size: 2rem;
}
.controls-area {
display: flex;
justify-content: center;
}
.action-btn {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.75rem 1.5rem;
border-radius: 6px;
font-size: 1rem;
cursor: pointer;
transition: opacity 0.2s;
}
.action-btn:hover {
opacity: 0.9;
}
.explanation {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
font-size: 0.85rem;
}
.explanation p {
margin: 0 0 0.5rem 0;
font-weight: 600;
color: var(--vp-c-text-1);
}
.explanation ul {
margin: 0;
padding-left: 1.2rem;
color: var(--vp-c-text-2);
line-height: 1.6;
}
.explanation code {
background: var(--vp-c-bg-soft);
padding: 0.1rem 0.3rem;
border-radius: 3px;
font-family: monospace;
}
.config-demo {
display: flex;
flex-direction: column;
gap: 1rem;
}
.multiplier-playground {
background: var(--vp-c-bg);
border-radius: 6px;
padding: 0.75rem;
}
.function-list {
display: flex;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.func-item {
flex: 1;
background: var(--vp-c-bg-soft);
border: 2px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.75rem;
text-align: center;
cursor: pointer;
transition: all 0.2s;
}
.func-item:hover {
border-color: var(--vp-c-brand);
}
.func-item.active {
border-color: var(--vp-c-brand);
background: var(--vp-c-brand-soft);
}
.func-name {
font-weight: 600;
font-family: monospace;
margin-bottom: 0.25rem;
color: var(--vp-c-text-1);
}
.func-desc {
font-size: 0.75rem;
color: var(--vp-c-text-3);
}
.multiplier-input {
display: flex;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.multiplier-input input {
flex: 1;
padding: 0.5rem;
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
background: var(--vp-c-bg-soft);
color: var(--vp-c-text-1);
}
.multiplier-input button {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.5rem 1rem;
border-radius: 6px;
cursor: pointer;
}
.multiply-result {
background: var(--vp-c-bg-soft);
border-radius: 6px;
padding: 1rem;
text-align: center;
}
.result-equation {
font-size: 1.2rem;
font-weight: bold;
color: var(--vp-c-brand);
}
.scope-chain-demo {
display: flex;
flex-direction: column;
gap: 1rem;
}
.nested-visual {
background: var(--vp-c-bg);
border-radius: 6px;
padding: 1rem;
}
.scope-level {
border: 2px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.75rem;
position: relative;
}
.scope-level.global {
background: #f5f5f5;
}
.scope-level.outer {
background: #e8f5e9;
margin: 0.5rem 0 0.5rem 0.5rem;
border-color: #c8e6c9;
}
.scope-level.inner {
background: #e3f2fd;
margin: 0.5rem 0 0 0.5rem;
border-color: #bbdefb;
}
.level-title {
font-weight: 600;
font-size: 0.85rem;
margin-bottom: 0.5rem;
text-transform: uppercase;
color: var(--vp-c-text-2);
}
.level-vars {
display: flex;
flex-wrap: wrap;
gap: 0.5rem;
}
.var-tag {
background: white;
padding: 0.25rem 0.5rem;
border-radius: 4px;
font-size: 0.8rem;
font-family: monospace;
border: 1px solid var(--vp-c-divider);
}
.lookup-demo {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
}
.lookup-title {
font-weight: 600;
margin-bottom: 0.5rem;
color: var(--vp-c-text-1);
}
.lookup-steps {
display: flex;
flex-direction: column;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.lookup-step {
display: flex;
gap: 0.5rem;
align-items: flex-start;
}
.step-num {
background: var(--vp-c-brand);
color: white;
width: 1.5rem;
height: 1.5rem;
border-radius: 50%;
display: flex;
align-items: center;
justify-content: center;
font-size: 0.75rem;
font-weight: 600;
flex-shrink: 0;
}
.step-content {
font-size: 0.85rem;
color: var(--vp-c-text-2);
line-height: 1.4;
}
.lookup-rule {
background: white;
padding: 0.5rem;
border-radius: 4px;
font-size: 0.85rem;
color: var(--vp-c-text-2);
}
.info-box {
background: var(--vp-c-bg-alt);
padding: 0.75rem;
border-radius: 6px;
font-size: 0.85rem;
color: var(--vp-c-text-2);
margin-top: 0.75rem;
display: flex;
gap: 0.25rem;
}
.info-box .icon { flex-shrink: 0; }
@media (max-width: 768px) {
.function-showcase {
grid-template-columns: 1fr;
}
.counter-demo {
grid-template-columns: 1fr;
}
}
</style>
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<template>
<div class="data-type-demo">
<div class="demo-header">
<span class="icon">🏷</span>
<span class="title">JavaScript 数据类型</span>
<span class="subtitle">原始类型 vs 引用类型</span>
</div>
<div class="intro-text">
想象你在外面<span class="highlight">租了个储物柜</span>
<span class="highlight">原始类型</span>像是把东西直接拿回家复制一份
<span class="highlight">引用类型</span>像是只拿了张写着地址的小纸条共享同一个位置
</div>
<div class="type-tabs">
<button
v-for="tab in tabs"
:key="tab.id"
@click="activeTab = tab.id"
class="tab-btn"
:class="{ active: activeTab === tab.id }"
>
{{ tab.label }}
</button>
</div>
<div class="content-area">
<!-- 原始类型 -->
<div v-if="activeTab === 'primitive'" class="primitive-types">
<div class="type-grid">
<div
v-for="type in primitiveTypes"
:key="type.name"
class="type-card"
@click="selectedType = type"
:class="{ selected: selectedType?.name === type.name }"
>
<div class="type-icon">{{ type.icon }}</div>
<div class="type-name">{{ type.name }}</div>
<div class="type-example">{{ type.example }}</div>
</div>
</div>
<div v-if="selectedType" class="type-detail">
<div class="detail-title">📝 {{ selectedType.name }} 详细说明</div>
<div class="detail-desc">{{ selectedType.description }}</div>
<div class="detail-note">
<strong>💡 关键特性</strong>{{ selectedType.note }}
</div>
</div>
</div>
<!-- 引用类型 -->
<div v-else-if="activeTab === 'reference'" class="reference-types">
<div class="comparison-box">
<div class="compare-side">
<div class="side-title">原始类型赋值</div>
<div class="code-example">
<div class="code-line">let a = 10</div>
<div class="code-line">let b = a</div>
<div class="code-line">b = 20</div>
<div class="code-line result">// a = 10 (不变)</div>
</div>
<div class="visual-box">
<div class="value-box">a = 10</div>
<div class="arrow">复制</div>
<div class="value-box">b = 20</div>
</div>
</div>
<div class="compare-side">
<div class="side-title">引用类型赋值</div>
<div class="code-example">
<div class="code-line">let obj1 = {x: 10}</div>
<div class="code-line">let obj2 = obj1</div>
<div class="code-line">obj2.x = 20</div>
<div class="code-line result">// obj1.x = 20 (变了!)</div>
</div>
<div class="visual-box">
<div class="ref-box">
<div>obj1 </div>
<div class="memory-box">{x: 20}</div>
</div>
<div class="arrow">指向同一位置</div>
<div class="ref-box">
<div>obj2 </div>
</div>
</div>
</div>
</div>
<div class="ref-types-list">
<div class="ref-type-item" v-for="type in referenceTypes" :key="type.name">
<div class="ref-icon">{{ type.icon }}</div>
<div class="ref-info">
<div class="ref-name">{{ type.name }}</div>
<div class="ref-desc">{{ type.description }}</div>
</div>
</div>
</div>
</div>
<!-- 类型转换 -->
<div v-else class="type-conversion">
<div class="conversion-playground">
<div class="input-section">
<label>输入一个值</label>
<input v-model="inputValue" type="text" placeholder="试试输入 '123' 或 'hello'" @keyup.enter="convertType" />
<button @click="convertType" class="convert-btn">转换</button>
</div>
<div class="results-section">
<div class="result-row">
<span class="result-label">String():</span>
<span class="result-value">{{ conversionResults.string }}</span>
</div>
<div class="result-row">
<span class="result-label">Number():</span>
<span class="result-value" :class="{ error: conversionResults.number === 'NaN' }">
{{ conversionResults.number }}
</span>
</div>
<div class="result-row">
<span class="result-label">Boolean():</span>
<span class="result-value">{{ conversionResults.boolean }}</span>
</div>
</div>
<div class="falsy-values">
<div class="falsy-title"> 转成 false 的值falsy values</div>
<div class="falsy-list">
<span v-for="val in falsyValues" :key="val" class="falsy-item">{{ val }}</span>
</div>
<div class="falsy-note">其他所有值包括空数组 []空对象 {}都转成 true</div>
</div>
</div>
</div>
</div>
<div class="info-box">
<span class="icon">💡</span>
<strong>核心思想</strong>
<span v-if="activeTab === 'primitive'">原始类型存储实际的值赋值时复制值它们是不可变的修改后创建新值</span>
<span v-else-if="activeTab === 'reference'">引用类型存储的是内存地址的引用赋值时复制引用多个变量可以指向同一个对象修改其中一个会影响所有引用</span>
<span v-else>类型转换是 JS 中常见的 bug 来源理解 falsy values 和隐式转换规则能避免很多问题使用 === 而不是 == 来避免自动类型转换</span>
</div>
</div>
</template>
<script setup>
import { ref, computed } from 'vue'
const activeTab = ref('primitive')
const selectedType = ref(null)
const inputValue = ref('')
const conversionResults = ref({
string: '-',
number: '-',
boolean: '-'
})
const tabs = [
{ id: 'primitive', label: '原始类型' },
{ id: 'reference', label: '引用类型' },
{ id: 'conversion', label: '类型转换' }
]
const primitiveTypes = [
{
name: 'Number',
icon: '🔢',
example: '42, 3.14, NaN',
description: '数字类型,包括整数和小数。NaN 表示"不是数字"。',
note: '所有数字都是浮点数,没有整数类型。特殊值:Infinity、-Infinity、NaN'
},
{
name: 'String',
icon: '📝',
example: '"hello", \'你好\'',
description: '字符串类型,用单引号或双引号包裹的文本。',
note: '字符串是不可变的,任何操作都会返回新的字符串。'
},
{
name: 'Boolean',
icon: '✅',
example: 'true, false',
description: '布尔类型,只有两个值:真或假。',
note: '常用于条件判断和逻辑运算。'
},
{
name: 'Undefined',
icon: '❓',
example: 'let x; // x 是 undefined',
description: '变量已声明但未赋值时的默认值。',
note: '表示"缺少值"。主动赋值 undefined 没有意义。'
},
{
name: 'Null',
icon: '🕳️',
example: 'let x = null;',
description: '表示"空值"或"无对象"。',
note: 'typeof null === "object" 是 JS 的历史 bug。'
},
{
name: 'Symbol',
icon: '🔑',
example: 'Symbol("id")',
description: 'ES6 新增,表示独一无二的值。',
note: '常用于对象属性的键,防止属性名冲突。'
},
{
name: 'BigInt',
icon: '🔢',
example: '9007199254740991n',
description: 'ES2020 新增,表示任意大的整数。',
note: '数字后面加 n。用于处理超大整数。'
}
]
const referenceTypes = [
{
name: 'Object',
icon: '📦',
description: '键值对集合,最常用的引用类型。数组、函数也是对象。'
},
{
name: 'Array',
icon: '📚',
description: '有序的数据集合,实际上是特殊的对象。'
},
{
name: 'Function',
icon: '⚙️',
description: '可执行的代码块,也是对象,可以赋值给变量。'
},
{
name: 'Date',
icon: '📅',
description: '日期和时间对象。'
},
{
name: 'RegExp',
icon: '🔍',
description: '正则表达式对象,用于模式匹配。'
}
]
const falsyValues = ['false', '0', '""', 'null', 'undefined', 'NaN']
const convertType = () => {
const val = inputValue.value
conversionResults.value = {
string: String(val),
number: Number(val).toString(),
boolean: Boolean(val).toString()
}
}
</script>
<style scoped>
.data-type-demo {
border: 1px solid var(--vp-c-divider);
border-radius: 8px;
background: var(--vp-c-bg-soft);
padding: 1rem;
}
.demo-header {
display: flex;
align-items: center;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.demo-header .icon { font-size: 1.25rem; }
.demo-header .title { font-weight: bold; font-size: 1rem; }
.demo-header .subtitle { color: var(--vp-c-text-2); font-size: 0.85rem; margin-left: 0.5rem; }
.intro-text {
font-size: 0.9rem;
line-height: 1.6;
margin-bottom: 1rem;
color: var(--vp-c-text-1);
}
.highlight {
background: var(--vp-c-brand-soft);
color: var(--vp-c-brand);
padding: 0.1rem 0.3rem;
border-radius: 4px;
font-weight: 500;
}
.type-tabs {
display: flex;
gap: 0.5rem;
margin-bottom: 1rem;
border-bottom: 1px solid var(--vp-c-divider);
padding-bottom: 0.5rem;
}
.tab-btn {
background: transparent;
border: none;
padding: 0.5rem 1rem;
cursor: pointer;
color: var(--vp-c-text-2);
font-size: 0.9rem;
border-radius: 6px;
transition: all 0.2s;
}
.tab-btn:hover {
background: var(--vp-c-bg-soft);
}
.tab-btn.active {
background: var(--vp-c-brand);
color: white;
}
.content-area {
min-height: 350px;
}
.type-grid {
display: grid;
grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
gap: 0.75rem;
margin-bottom: 1rem;
}
.type-card {
background: var(--vp-c-bg);
border: 2px solid var(--vp-c-divider);
border-radius: 8px;
padding: 0.75rem;
text-align: center;
cursor: pointer;
transition: all 0.2s;
}
.type-card:hover {
border-color: var(--vp-c-brand);
transform: translateY(-2px);
}
.type-card.selected {
border-color: var(--vp-c-brand);
background: var(--vp-c-brand-soft);
}
.type-icon {
font-size: 2rem;
margin-bottom: 0.5rem;
}
.type-name {
font-weight: 600;
margin-bottom: 0.25rem;
color: var(--vp-c-text-1);
}
.type-example {
font-size: 0.75rem;
color: var(--vp-c-text-3);
font-family: monospace;
}
.type-detail {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
margin-top: 1rem;
}
.detail-title {
font-weight: 600;
margin-bottom: 0.5rem;
color: var(--vp-c-text-1);
}
.detail-desc {
font-size: 0.9rem;
color: var(--vp-c-text-2);
margin-bottom: 0.5rem;
line-height: 1.5;
}
.detail-note {
font-size: 0.85rem;
color: var(--vp-c-brand);
background: var(--vp-c-brand-soft);
padding: 0.5rem;
border-radius: 4px;
}
.comparison-box {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
margin-bottom: 1rem;
}
.compare-side {
background: var(--vp-c-bg);
border-radius: 6px;
padding: 0.75rem;
border: 1px solid var(--vp-c-divider);
}
.side-title {
font-weight: 600;
margin-bottom: 0.5rem;
color: var(--vp-c-text-1);
text-align: center;
}
.code-example {
background: #1e1e1e;
border-radius: 4px;
padding: 0.5rem;
font-family: monospace;
font-size: 0.8rem;
margin-bottom: 0.5rem;
}
.code-line {
padding: 0.15rem 0;
color: #d4d4d4;
}
.code-line.result {
color: #6a9955;
margin-top: 0.25rem;
}
.visual-box {
display: flex;
align-items: center;
justify-content: center;
gap: 0.5rem;
font-size: 0.8rem;
}
.value-box {
background: var(--vp-c-bg-soft);
padding: 0.5rem;
border-radius: 4px;
border: 2px solid var(--vp-c-brand);
}
.ref-box {
display: flex;
align-items: center;
gap: 0.25rem;
}
.memory-box {
background: var(--vp-c-brand-soft);
padding: 0.5rem;
border-radius: 4px;
border: 2px solid var(--vp-c-brand);
}
.arrow {
color: var(--vp-c-text-3);
font-size: 0.75rem;
text-align: center;
}
.ref-types-list {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.ref-type-item {
display: flex;
gap: 0.75rem;
padding: 0.75rem;
background: var(--vp-c-bg);
border-radius: 6px;
align-items: center;
}
.ref-icon {
font-size: 1.5rem;
}
.ref-name {
font-weight: 600;
color: var(--vp-c-text-1);
}
.ref-desc {
font-size: 0.85rem;
color: var(--vp-c-text-2);
}
.conversion-playground {
display: flex;
flex-direction: column;
gap: 1rem;
}
.input-section {
display: flex;
gap: 0.5rem;
align-items: center;
}
.input-section label {
font-size: 0.9rem;
color: var(--vp-c-text-1);
white-space: nowrap;
}
.input-section input {
flex: 1;
padding: 0.5rem;
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
background: var(--vp-c-bg);
color: var(--vp-c-text-1);
}
.convert-btn {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.5rem 1rem;
border-radius: 6px;
cursor: pointer;
}
.results-section {
background: var(--vp-c-bg);
border-radius: 6px;
padding: 0.75rem;
}
.result-row {
display: flex;
justify-content: space-between;
padding: 0.4rem 0;
border-bottom: 1px solid var(--vp-c-divider);
}
.result-row:last-child {
border-bottom: none;
}
.result-label {
font-weight: 600;
color: var(--vp-c-text-2);
font-family: monospace;
}
.result-value {
font-family: monospace;
color: var(--vp-c-brand);
}
.result-value.error {
color: #f48771;
}
.falsy-values {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
}
.falsy-title {
font-weight: 600;
margin-bottom: 0.5rem;
color: var(--vp-c-text-1);
}
.falsy-list {
display: flex;
flex-wrap: wrap;
gap: 0.5rem;
margin-bottom: 0.5rem;
}
.falsy-item {
background: var(--vp-c-bg);
padding: 0.25rem 0.5rem;
border-radius: 4px;
font-family: monospace;
font-size: 0.85rem;
color: var(--vp-c-brand);
}
.falsy-note {
font-size: 0.85rem;
color: var(--vp-c-text-2);
}
.info-box {
background: var(--vp-c-bg-alt);
padding: 0.75rem;
border-radius: 6px;
font-size: 0.85rem;
color: var(--vp-c-text-2);
margin-top: 0.75rem;
display: flex;
gap: 0.25rem;
}
.info-box .icon { flex-shrink: 0; }
@media (max-width: 768px) {
.comparison-box {
grid-template-columns: 1fr;
}
}
</style>
@@ -0,0 +1,827 @@
<template>
<div class="prototype-demo">
<div class="demo-header">
<span class="icon">🧬</span>
<span class="title">原型与继承</span>
<span class="subtitle">理解 JavaScript 的原型链机制</span>
</div>
<div class="intro-text">
想象你有本<span class="highlight">秘籍</span>上面记载了很多通用技能当你需要某个技能时
先翻翻自己的<span class="highlight">技能书</span>没有就去翻<span class="highlight">师傅的秘籍</span>
还没有就去翻<span class="highlight">师傅的师傅的秘籍</span>这条<span class="highlight">查找链</span>就是原型链
</div>
<div class="demo-tabs">
<button
v-for="tab in tabs"
:key="tab.id"
@click="activeTab = tab.id"
class="tab-btn"
:class="{ active: activeTab === tab.id }"
>
{{ tab.label }}
</button>
</div>
<!-- 原型基础 -->
<div v-if="activeTab === 'basic'" class="tab-content">
<div class="concept-explanation">
<div class="code-panel">
<div class="code-title">创建对象的方式</div>
<div class="code-block">
<div class="code-line comment">// 方式 1:对象字面量</div>
<div class="code-line">const obj1 = { name: "对象1" }</div>
<div class="code-line">obj1.__proto__ === Object.prototype <span class="comment">// true</span></div>
<div class="code-line"></div>
<div class="code-line comment">// 方式 2:构造函数</div>
<div class="code-line">function Person(name) {</div>
<div class="code-line indent">this.name = name</div>
<div class="code-line">}</div>
<div class="code-line">const p = new Person("张三")</div>
<div class="code-line">p.__proto__ === Person.prototype <span class="comment">// true</span></div>
</div>
</div>
<div class="prototype-visual">
<div class="prototype-chain">
<div class="chain-node" :class="{ active: chainLevel >= 0 }" @click="chainLevel = 0">
<div class="node-title">对象实例 (p)</div>
<div class="node-content">
<div class="property">name: "张三"</div>
<div class="proto-link">__proto__ </div>
</div>
</div>
<div class="chain-arrow" v-if="chainLevel >= 0"> 查找</div>
<div class="chain-node constructor" :class="{ active: chainLevel >= 1 }" @click="chainLevel = 1">
<div class="node-title">Person.prototype</div>
<div class="node-content">
<div class="method">constructor: Person</div>
<div class="proto-link">__proto__ </div>
</div>
</div>
<div class="chain-arrow" v-if="chainLevel >= 1"> 查找</div>
<div class="chain-node object" :class="{ active: chainLevel >= 2 }" @click="chainLevel = 2">
<div class="node-title">Object.prototype</div>
<div class="node-content">
<div class="method">toString()</div>
<div class="method">hasOwnProperty()</div>
<div class="proto-link">__proto__ null</div>
</div>
</div>
</div>
<div class="chain-explanation">
<div v-if="chainLevel === 0">
<strong>实例对象</strong>
<p>访问 p.name 在自己的属性中找到 返回 "张三"</p>
</div>
<div v-else-if="chainLevel === 1">
<strong>Person 原型</strong>
<p>访问 p.toString() 实例中没有 向上查找 Person.prototype 中没有 继续向上</p>
</div>
<div v-else>
<strong>Object 原型链的顶端</strong>
<p>找到了 toString() 方法这是所有对象的祖先提供的方法</p>
</div>
</div>
</div>
</div>
</div>
<!-- 原型继承 -->
<div v-else-if="activeTab === 'inheritance'" class="tab-content">
<div class="inheritance-demo">
<div class="inheritance-code">
<div class="code-title">原型继承示例</div>
<div class="code-block">
<div class="code-line comment">// 父类构造函数</div>
<div class="code-line">function Animal(name) {</div>
<div class="code-line indent">this.name = name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">Animal.prototype.eat = function() {</div>
<div class="code-line indent">return this.name + " 在吃东西"</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line comment">// 子类构造函数</div>
<div class="code-line">function Dog(name, breed) {</div>
<div class="code-line indent">Animal.call(this, name) <span class="comment">// 继承属性</span></div>
<div class="code-line indent">this.breed = breed</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line comment">// 继承方法</div>
<div class="code-line">Dog.prototype = Object.create(Animal.prototype)</div>
<div class="code-line">Dog.prototype.constructor = Dog</div>
</div>
</div>
<div class="inheritance-visual">
<div class="class-diagram">
<div class="class-box parent">
<div class="class-title">Animal (父类)</div>
<div class="class-content">
<div class="class-section">
<div class="section-title">属性</div>
<div class="section-item">name: String</div>
</div>
<div class="class-section">
<div class="section-title">方法 (prototype)</div>
<div class="section-item">eat()</div>
</div>
</div>
</div>
<div class="inherit-arrow"> 继承</div>
<div class="class-box child">
<div class="class-title">Dog (子类)</div>
<div class="class-content">
<div class="class-section">
<div class="section-title">属性</div>
<div class="section-item">name: String</div>
<div class="section-item">breed: String</div>
</div>
<div class="class-section">
<div class="section-title">方法 (prototype)</div>
<div class="section-item">eat() <span class="inherited">[继承]</span></div>
<div class="section-item">bark() <span class="own">[新增]</span></div>
</div>
</div>
</div>
</div>
<div class="inheritance-playground">
<div class="playground-title">试试创建实例</div>
<div class="input-group">
<input v-model="dogName" placeholder="狗狗名字" />
<input v-model="dogBreed" placeholder="品种" />
<button @click="createDog">创建</button>
</div>
<div v-if="dogInstance" class="instance-result">
<div class="result-item">
<span class="label">名字</span>
<span class="value">{{ dogInstance.name }}</span>
</div>
<div class="result-item">
<span class="label">品种</span>
<span class="value">{{ dogInstance.breed }}</span>
</div>
<div class="result-item">
<span class="label">调用 eat()</span>
<button @click="callEat" class="action-btn">调用</button>
<span v-if="eatResult" class="method-result">{{ eatResult }}</span>
</div>
</div>
</div>
</div>
</div>
</div>
<!-- class 语法 -->
<div v-else class="tab-content">
<div class="class-syntax-demo">
<div class="syntax-comparison">
<div class="syntax-panel old">
<div class="panel-title">ES5 构造函数</div>
<div class="code-block">
<div class="code-line">function Person(name) {</div>
<div class="code-line indent">this.name = name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">Person.prototype.greet = function() {</div>
<div class="code-line indent">return "你好,我是" + this.name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">const p = new Person("小明")</div>
</div>
</div>
<div class="syntax-panel new">
<div class="panel-title">ES6 class 语法</div>
<div class="code-block">
<div class="code-line">class Person {</div>
<div class="code-line indent">constructor(name) {</div>
<div class="code-line indent indent">this.name = name</div>
<div class="code-line indent">}</div>
<div class="code-line"></div>
<div class="code-line indent">greet() {</div>
<div class="code-line indent indent">return "你好,我是" + this.name</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">const p = new Person("小明")</div>
</div>
</div>
</div>
<div class="class-features">
<div class="feature-card">
<div class="feature-icon">🎯</div>
<div class="feature-title">更清晰的语法</div>
<div class="feature-desc">class 语法让面向对象编程更直观但本质还是基于原型</div>
</div>
<div class="feature-card">
<div class="feature-icon">🔗</div>
<div class="feature-title">继承更简单</div>
<div class="feature-desc">使用 extends 关键字实现继承代码更简洁</div>
</div>
<div class="feature-card">
<div class="feature-icon"></div>
<div class="feature-title">注意</div>
<div class="feature-desc">class 只是语法糖底层仍然是原型链机制</div>
</div>
</div>
<div class="inheritance-example">
<div class="code-title">class 继承示例</div>
<div class="code-block">
<div class="code-line">class Animal {</div>
<div class="code-line indent">constructor(name) {</div>
<div class="code-line indent indent">this.name = name</div>
<div class="code-line indent">}</div>
<div class="code-line indent">eat() {</div>
<div class="code-line indent indent">return this.name + " 在吃东西"</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">class Dog extends Animal {</div>
<div class="code-line indent">constructor(name, breed) {</div>
<div class="code-line indent indent">super(name) <span class="comment">// 调用父类构造函数</span></div>
<div class="code-line indent indent">this.breed = breed</div>
<div class="code-line indent">}</div>
<div class="code-line indent">bark() {</div>
<div class="code-line indent indent">return "汪汪!"</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
</div>
</div>
</div>
</div>
<div class="key-points">
<div class="point-title">🎯 核心要点</div>
<ul class="point-list">
<li>每个对象都有 <code>__proto__</code> 属性指向其构造函数的 <code>prototype</code></li>
<li>访问对象属性时先在自身查找找不到就沿着原型链向上查找</li>
<li>原型链顶端是 <code>Object.prototype</code>它的 <code>__proto__</code> <code>null</code></li>
<li><code>class</code> 是语法糖本质仍然是原型继承</li>
</ul>
</div>
<div class="info-box">
<span class="icon">💡</span>
<strong>核心思想</strong>
<span v-if="activeTab === 'basic'">JavaScript 通过原型链实现继承而不是像其他语言那样使用类每个对象都有一个原型对象对象以其原型为模板从原型继承方法和属性这种"原型式继承"机制让 JavaScript 更加灵活</span>
<span v-else-if="activeTab === 'inheritance'">原型继承让对象可以共享方法节省内存子类通过原型链继承父类的方法同时可以添加自己的方法理解原型链是掌握 JavaScript 面向对象编程的关键</span>
<span v-else>ES6 class 语法让面向对象编程更加清晰易读但它只是语法糖底层仍然是原型链使用 class 可以让代码更接近传统面向对象语言的风格降低学习成本</span>
</div>
</div>
</template>
<script setup>
import { ref } from 'vue'
const activeTab = ref('basic')
const chainLevel = ref(0)
const dogName = ref('')
const dogBreed = ref('')
const dogInstance = ref(null)
const eatResult = ref('')
const tabs = [
{ id: 'basic', label: '原型基础' },
{ id: 'inheritance', label: '原型继承' },
{ id: 'class', label: 'class 语法' }
]
const createDog = () => {
if (dogName.value && dogBreed.value) {
dogInstance.value = {
name: dogName.value,
breed: dogBreed.value
}
eatResult.value = ''
}
}
const callEat = () => {
if (dogInstance.value) {
eatResult.value = `${dogInstance.value.name} 在吃东西`
}
}
</script>
<style scoped>
.prototype-demo {
border: 1px solid var(--vp-c-divider);
border-radius: 8px;
background: var(--vp-c-bg-soft);
padding: 1rem;
}
.demo-header {
display: flex;
align-items: center;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.demo-header .icon { font-size: 1.25rem; }
.demo-header .title { font-weight: bold; font-size: 1rem; }
.demo-header .subtitle { color: var(--vp-c-text-2); font-size: 0.85rem; margin-left: 0.5rem; }
.intro-text {
font-size: 0.9rem;
line-height: 1.6;
margin-bottom: 1rem;
color: var(--vp-c-text-1);
}
.highlight {
background: var(--vp-c-brand-soft);
color: var(--vp-c-brand);
padding: 0.1rem 0.3rem;
border-radius: 4px;
font-weight: 500;
}
.demo-tabs {
display: flex;
gap: 0.5rem;
margin-bottom: 1rem;
border-bottom: 1px solid var(--vp-c-divider);
padding-bottom: 0.5rem;
}
.tab-btn {
background: transparent;
border: none;
padding: 0.5rem 1rem;
cursor: pointer;
color: var(--vp-c-text-2);
font-size: 0.9rem;
border-radius: 6px;
transition: all 0.2s;
}
.tab-btn:hover {
background: var(--vp-c-bg-soft);
}
.tab-btn.active {
background: var(--vp-c-brand);
color: white;
}
.tab-content {
min-height: 380px;
}
.concept-explanation {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
}
.code-panel {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.75rem;
color: #d4d4d4;
}
.code-title {
color: #888;
font-size: 0.7rem;
margin-bottom: 0.5rem;
text-transform: uppercase;
}
.code-block {
line-height: 1.5;
}
.code-line {
padding: 0.1rem 0;
}
.code-line.indent {
padding-left: 1.5rem;
}
.code-line .comment {
color: #6a9955;
}
.prototype-visual {
display: flex;
flex-direction: column;
gap: 0.75rem;
}
.prototype-chain {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.chain-node {
background: var(--vp-c-bg);
border: 2px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.75rem;
cursor: pointer;
transition: all 0.2s;
}
.chain-node:hover {
border-color: var(--vp-c-brand);
}
.chain-node.active {
border-color: var(--vp-c-brand);
background: var(--vp-c-brand-soft);
}
.chain-node.constructor {
border-color: #c8e6c9;
}
.chain-node.constructor.active {
background: #e8f5e9;
}
.chain-node.object {
border-color: #bbdefb;
}
.chain-node.object.active {
background: #e3f2fd;
}
.node-title {
font-weight: 600;
color: var(--vp-c-text-1);
margin-bottom: 0.5rem;
font-size: 0.85rem;
}
.node-content {
display: flex;
flex-direction: column;
gap: 0.25rem;
}
.property {
background: var(--vp-c-bg-soft);
padding: 0.25rem 0.5rem;
border-radius: 4px;
font-family: monospace;
font-size: 0.75rem;
color: var(--vp-c-text-2);
}
.method {
background: #e3f2fd;
padding: 0.25rem 0.5rem;
border-radius: 4px;
font-family: monospace;
font-size: 0.75rem;
color: #1976d2;
}
.proto-link {
color: var(--vp-c-brand);
font-family: monospace;
font-size: 0.8rem;
margin-top: 0.25rem;
}
.chain-arrow {
text-align: center;
color: var(--vp-c-brand);
font-weight: 600;
font-size: 0.85rem;
}
.chain-explanation {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
font-size: 0.85rem;
}
.chain-explanation strong {
color: var(--vp-c-text-1);
display: block;
margin-bottom: 0.5rem;
}
.chain-explanation p {
color: var(--vp-c-text-2);
line-height: 1.5;
margin: 0;
}
.inheritance-demo {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
}
.inheritance-code {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.7rem;
color: #d4d4d4;
}
.inheritance-visual {
display: flex;
flex-direction: column;
gap: 0.75rem;
}
.class-diagram {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.class-box {
background: var(--vp-c-bg);
border: 2px solid var(--vp-c-divider);
border-radius: 8px;
padding: 0.75rem;
}
.class-box.parent {
border-color: #c8e6c9;
}
.class-box.child {
border-color: var(--vp-c-brand);
}
.class-title {
font-weight: 600;
color: var(--vp-c-text-1);
margin-bottom: 0.5rem;
font-size: 0.85rem;
}
.class-content {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.class-section {
background: var(--vp-c-bg-soft);
border-radius: 4px;
padding: 0.5rem;
}
.section-title {
font-weight: 600;
color: var(--vp-c-text-2);
margin-bottom: 0.25rem;
font-size: 0.75rem;
}
.section-item {
font-family: monospace;
font-size: 0.75rem;
padding: 0.15rem 0;
color: var(--vp-c-text-2);
}
.inherited {
color: #4caf50;
font-size: 0.7rem;
}
.own {
color: var(--vp-c-brand);
font-size: 0.7rem;
}
.inherit-arrow {
text-align: center;
color: var(--vp-c-brand);
font-weight: 600;
}
.inheritance-playground {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
}
.playground-title {
font-weight: 600;
margin-bottom: 0.5rem;
font-size: 0.85rem;
color: var(--vp-c-text-1);
}
.input-group {
display: flex;
gap: 0.5rem;
margin-bottom: 0.5rem;
}
.input-group input {
flex: 1;
padding: 0.4rem;
border: 1px solid var(--vp-c-divider);
border-radius: 4px;
background: var(--vp-c-bg);
color: var(--vp-c-text-1);
font-size: 0.85rem;
}
.input-group button {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.4rem 0.75rem;
border-radius: 4px;
cursor: pointer;
font-size: 0.85rem;
}
.instance-result {
background: var(--vp-c-bg);
border-radius: 4px;
padding: 0.5rem;
}
.result-item {
display: flex;
align-items: center;
gap: 0.5rem;
padding: 0.3rem 0;
font-size: 0.85rem;
}
.result-item .label {
font-weight: 600;
color: var(--vp-c-text-2);
min-width: 4rem;
}
.result-item .value {
color: var(--vp-c-text-1);
}
.action-btn {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.25rem 0.5rem;
border-radius: 4px;
cursor: pointer;
font-size: 0.75rem;
}
.method-result {
color: var(--vp-c-brand);
font-weight: 600;
}
.class-syntax-demo {
display: flex;
flex-direction: column;
gap: 1rem;
}
.syntax-comparison {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
}
.syntax-panel {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.75rem;
color: #d4d4d4;
}
.syntax-panel.new {
border: 2px solid var(--vp-c-brand);
}
.panel-title {
color: #888;
font-size: 0.7rem;
margin-bottom: 0.5rem;
text-transform: uppercase;
}
.class-features {
display: grid;
grid-template-columns: repeat(3, 1fr);
gap: 0.75rem;
}
.feature-card {
background: var(--vp-c-bg);
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.75rem;
text-align: center;
}
.feature-icon {
font-size: 1.5rem;
margin-bottom: 0.5rem;
}
.feature-title {
font-weight: 600;
color: var(--vp-c-text-1);
margin-bottom: 0.25rem;
font-size: 0.85rem;
}
.feature-desc {
font-size: 0.8rem;
color: var(--vp-c-text-2);
line-height: 1.4;
}
.inheritance-example {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.75rem;
color: #d4d4d4;
}
.key-points {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
margin-top: 1rem;
}
.point-title {
font-weight: 600;
color: var(--vp-c-text-1);
margin-bottom: 0.5rem;
font-size: 0.9rem;
}
.point-list {
margin: 0;
padding-left: 1.2rem;
color: var(--vp-c-text-2);
font-size: 0.85rem;
line-height: 1.6;
}
.point-list code {
background: var(--vp-c-bg-soft);
padding: 0.1rem 0.3rem;
border-radius: 3px;
font-family: monospace;
}
.info-box {
background: var(--vp-c-bg-alt);
padding: 0.75rem;
border-radius: 6px;
font-size: 0.85rem;
color: var(--vp-c-text-2);
margin-top: 0.75rem;
display: flex;
gap: 0.25rem;
}
.info-box .icon { flex-shrink: 0; }
@media (max-width: 768px) {
.concept-explanation,
.inheritance-demo,
.syntax-comparison,
.class-features {
grid-template-columns: 1fr;
}
}
</style>
@@ -0,0 +1,899 @@
<template>
<div class="this-context-demo">
<div class="demo-header">
<span class="icon">🎯</span>
<span class="title">this 与执行上下文</span>
<span class="subtitle">理解 this 的指向规则</span>
</div>
<div class="intro-text">
想象<span class="highlight">this</span>就像一个<span class="highlight">指针</span>
指向"当前正在执行的主角"不同场景下主角会变化
有时是<span class="highlight">对象自己</span>有时是<span class="highlight">全局环境</span>还有时完全取决于<span class="highlight">谁在调用</span>
</div>
<div class="scenario-selector">
<button
v-for="scenario in scenarios"
:key="scenario.id"
@click="activeScenario = scenario.id"
class="scenario-btn"
:class="{ active: activeScenario === scenario.id }"
>
{{ scenario.label }}
</button>
</div>
<!-- 方法调用 -->
<div v-if="activeScenario === 'method'" class="scenario-content">
<div class="split-view">
<div class="code-panel">
<div class="code-title">对象方法调用</div>
<div class="code-block">
<div class="code-line">const person = {</div>
<div class="code-line indent">name: "张三",</div>
<div class="code-line indent">greet: function() {</div>
<div class="code-line indent indent">return "你好,我是" + this.name</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">person.greet() <span class="comment">// this → person</span></div>
</div>
</div>
<div class="visual-panel">
<div class="object-visual">
<div class="object-box">
<div class="object-title">person 对象</div>
<div class="object-content">
<div class="property">name: "张三"</div>
<div class="method" @click="simulateMethodCall">
greet: function() { ... }
</div>
</div>
</div>
<div class="arrow-indicator">
<div class="this-pointer">this </div>
</div>
<div v-if="methodCallResult" class="result-box">
{{ methodCallResult }}
</div>
</div>
<div class="rule-box">
<div class="rule-title">规则对象方法</div>
<div class="rule-content">通过对象调用方法时<code>this</code> 指向该对象</div>
</div>
</div>
</div>
</div>
<!-- 普通函数 -->
<div v-else-if="activeScenario === 'function'" class="scenario-content">
<div class="split-view">
<div class="code-panel">
<div class="code-title">普通函数调用</div>
<div class="code-block">
<div class="code-line">function show() {</div>
<div class="code-line indent">return this === window</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">show() <span class="comment">// this → window (浏览器)</span></div>
<div class="code-line"></div>
<div class="code-line comment">// 严格模式下是 undefined</div>
</div>
</div>
<div class="visual-panel">
<div class="function-visual">
<div class="global-window">
<div class="window-title">window (全局对象)</div>
<div class="window-content">
<div class="global-item">show 函数在这里</div>
<div class="global-item">this window</div>
</div>
</div>
</div>
<div class="mode-toggle">
<button @click="strictMode = !strictMode" class="toggle-btn">
{{ strictMode ? '严格模式:开' : '严格模式:关' }}
</button>
<div class="mode-result">
this = {{ strictMode ? 'undefined' : 'window' }}
</div>
</div>
<div class="rule-box">
<div class="rule-title">规则普通函数</div>
<div class="rule-content">
非严格模式<code>this</code> 指向全局对象<br>
严格模式<code>this</code> <code>undefined</code>
</div>
</div>
</div>
</div>
</div>
<!-- 构造函数 -->
<div v-else-if="activeScenario === 'constructor'" class="scenario-content">
<div class="split-view">
<div class="code-panel">
<div class="code-title">构造函数调用</div>
<div class="code-block">
<div class="code-line">function Person(name) {</div>
<div class="code-line indent">this.name = name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">const p1 = new Person("李四")</div>
<div class="code-line">const p2 = new Person("王五")</div>
<div class="code-line"></div>
<div class="code-line comment">// p1.name = "李四"</div>
<div class="code-line comment">// p2.name = "王五"</div>
</div>
</div>
<div class="visual-panel">
<div class="constructor-visual">
<div class="constructor-process">
<div class="process-step">
<span class="step-num">1</span>
<span>创建新对象</span>
</div>
<div class="process-arrow"></div>
<div class="process-step">
<span class="step-num">2</span>
<span>this 指向新对象</span>
</div>
<div class="process-arrow"></div>
<div class="process-step">
<span class="step-num">3</span>
<span>执行构造函数</span>
</div>
<div class="process-arrow"></div>
<div class="process-step">
<span class="step-num">4</span>
<span>返回新对象</span>
</div>
</div>
<div class="object-comparison">
<div class="obj-instance">
<div class="obj-title">p1</div>
<div class="obj-content">name: "李四"</div>
</div>
<div class="obj-instance">
<div class="obj-title">p2</div>
<div class="obj-content">name: "王五"</div>
</div>
</div>
</div>
<div class="rule-box">
<div class="rule-title">规则new 调用</div>
<div class="rule-content">
使用 <code>new</code> 调用函数时<code>this</code> 指向新创建的对象
</div>
</div>
</div>
</div>
</div>
<!-- call/apply/bind -->
<div v-else-if="activeScenario === 'explicit'" class="scenario-content">
<div class="split-view">
<div class="code-panel">
<div class="code-title">显式绑定 (call/apply/bind)</div>
<div class="code-block">
<div class="code-line">function greet() {</div>
<div class="code-line indent">return "我是" + this.name</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">const person = { name: "小明" }</div>
<div class="code-line"></div>
<div class="code-line">greet.call(person) <span class="comment">// 显式指定 this</span></div>
<div class="code-line">greet.apply(person)</div>
<div class="code-line">const bound = greet.bind(person)</div>
</div>
</div>
<div class="visual-panel">
<div class="binding-visual">
<div class="function-box">
<div class="box-title">greet 函数</div>
<div class="box-content">this.name</div>
</div>
<div class="binding-methods">
<div class="binding-item" @click="simulateCall" :class="{ active: bindingMethod === 'call' }">
<div class="method-name">call(person)</div>
<div class="method-desc">立即调用this person</div>
</div>
<div class="binding-item" @click="simulateApply" :class="{ active: bindingMethod === 'apply' }">
<div class="method-name">apply(person)</div>
<div class="method-desc"> call参数为数组</div>
</div>
<div class="binding-item" @click="simulateBind" :class="{ active: bindingMethod === 'bind' }">
<div class="method-name">bind(person)</div>
<div class="method-desc">返回新函数this 固定</div>
</div>
</div>
<div v-if="bindingResult" class="binding-result">
{{ bindingResult }}
</div>
</div>
<div class="rule-box">
<div class="rule-title">规则显式绑定</div>
<div class="rule-content">
<code>call/apply/bind</code> 可以显式指定 <code>this</code> 的指向
</div>
</div>
</div>
</div>
</div>
<!-- 箭头函数 -->
<div v-else class="scenario-content">
<div class="split-view">
<div class="code-panel">
<div class="code-title">箭头函数的 this</div>
<div class="code-block">
<div class="code-line">const person = {</div>
<div class="code-line indent">name: "小红",</div>
<div class="code-line indent">greet: function() {</div>
<div class="code-line indent indent">setTimeout(() => {</div>
<div class="code-line indent indent indent">console.log(this.name)</div>
<div class="code-line indent indent">}, 1000)</div>
<div class="code-line indent">}</div>
<div class="code-line">}</div>
<div class="code-line"></div>
<div class="code-line">person.greet() <span class="comment">// 输出 "小红"</span></div>
</div>
</div>
<div class="visual-panel">
<div class="arrow-function-visual">
<div class="outer-context">
<div class="context-title">外层作用域 (person)</div>
<div class="context-content">
<div class="context-item">this.name = "小红"</div>
</div>
</div>
<div class="arrow-capture">
<div class="capture-title">箭头函数捕获外层 this</div>
<div class="capture-arrow"> 继承 this</div>
</div>
<div class="inner-context">
<div class="context-title">箭头函数内部</div>
<div class="context-content">
<div class="context-item">this 外层的 this</div>
</div>
</div>
</div>
<div class="rule-box">
<div class="rule-title">规则箭头函数</div>
<div class="rule-content">
箭头函数没有自己的 <code>this</code>它继承外层作用域的 <code>this</code>
</div>
</div>
</div>
</div>
</div>
<div class="quick-reference">
<div class="reference-title">📋 this 指向速查表</div>
<div class="reference-table">
<div class="ref-row header">
<span>调用方式</span>
<span>this 指向</span>
</div>
<div class="ref-row">
<span>obj.method()</span>
<span>obj</span>
</div>
<div class="ref-row">
<span>func()</span>
<span>window / undefined</span>
</div>
<div class="ref-row">
<span>new Func()</span>
<span>新创建的对象</span>
</div>
<div class="ref-row">
<span>func.call(obj)</span>
<span>obj</span>
</div>
<div class="ref-row">
<span>箭头函数</span>
<span>外层作用域的 this</span>
</div>
</div>
</div>
<div class="info-box">
<span class="icon">💡</span>
<strong>核心思想</strong>
<span>this 的值是在函数调用时确定的不是定义时确定的关键要看"函数是如何被调用的"而不是"函数在哪里定义"箭头函数是例外它没有自己的 this从外层作用域继承</span>
</div>
</div>
</template>
<script setup>
import { ref } from 'vue'
const activeScenario = ref('method')
const strictMode = ref(false)
const bindingMethod = ref('')
const methodCallResult = ref('')
const bindingResult = ref('')
const scenarios = [
{ id: 'method', label: '对象方法' },
{ id: 'function', label: '普通函数' },
{ id: 'constructor', label: '构造函数' },
{ id: 'explicit', label: 'call/apply/bind' },
{ id: 'arrow', label: '箭头函数' }
]
const simulateMethodCall = () => {
methodCallResult.value = '你好,我是张三'
setTimeout(() => {
methodCallResult.value = ''
}, 2000)
}
const simulateCall = () => {
bindingMethod.value = 'call'
bindingResult.value = '我是小明 (通过 call 绑定)'
}
const simulateApply = () => {
bindingMethod.value = 'apply'
bindingResult.value = '我是小明 (通过 apply 绑定)'
}
const simulateBind = () => {
bindingMethod.value = 'bind'
bindingResult.value = '我是小明 (通过 bind 绑定,返回新函数)'
}
</script>
<style scoped>
.this-context-demo {
border: 1px solid var(--vp-c-divider);
border-radius: 8px;
background: var(--vp-c-bg-soft);
padding: 1rem;
}
.demo-header {
display: flex;
align-items: center;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.demo-header .icon { font-size: 1.25rem; }
.demo-header .title { font-weight: bold; font-size: 1rem; }
.demo-header .subtitle { color: var(--vp-c-text-2); font-size: 0.85rem; margin-left: 0.5rem; }
.intro-text {
font-size: 0.9rem;
line-height: 1.6;
margin-bottom: 1rem;
color: var(--vp-c-text-1);
}
.highlight {
background: var(--vp-c-brand-soft);
color: var(--vp-c-brand);
padding: 0.1rem 0.3rem;
border-radius: 4px;
font-weight: 500;
}
.scenario-selector {
display: flex;
gap: 0.5rem;
margin-bottom: 1rem;
flex-wrap: wrap;
}
.scenario-btn {
background: var(--vp-c-bg);
border: 1px solid var(--vp-c-divider);
padding: 0.5rem 1rem;
border-radius: 6px;
cursor: pointer;
font-size: 0.85rem;
transition: all 0.2s;
}
.scenario-btn:hover {
border-color: var(--vp-c-brand);
}
.scenario-btn.active {
background: var(--vp-c-brand);
color: white;
border-color: var(--vp-c-brand);
}
.scenario-content {
min-height: 350px;
}
.split-view {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
}
.code-panel {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.8rem;
color: #d4d4d4;
}
.code-title {
color: #888;
font-size: 0.7rem;
margin-bottom: 0.5rem;
text-transform: uppercase;
}
.code-block {
line-height: 1.5;
}
.code-line {
padding: 0.1rem 0;
}
.code-line.indent {
padding-left: 1.5rem;
}
.code-line.indent.indent {
padding-left: 3rem;
}
.code-line .comment {
color: #6a9955;
}
.code-line code {
background: #333;
padding: 0.1rem 0.3rem;
border-radius: 3px;
}
.visual-panel {
display: flex;
flex-direction: column;
gap: 0.75rem;
}
.object-visual {
display: flex;
flex-direction: column;
align-items: center;
gap: 0.75rem;
}
.object-box {
background: var(--vp-c-bg);
border: 2px solid var(--vp-c-brand);
border-radius: 8px;
padding: 0.75rem;
width: 100%;
}
.object-title {
font-weight: 600;
color: var(--vp-c-brand);
margin-bottom: 0.5rem;
font-size: 0.9rem;
}
.object-content {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.property, .method {
background: var(--vp-c-bg-soft);
padding: 0.4rem;
border-radius: 4px;
font-family: monospace;
font-size: 0.8rem;
}
.method {
cursor: pointer;
transition: background 0.2s;
}
.method:hover {
background: var(--vp-c-brand-soft);
}
.arrow-indicator {
text-align: center;
}
.this-pointer {
background: var(--vp-c-brand);
color: white;
padding: 0.3rem 0.6rem;
border-radius: 4px;
font-size: 0.85rem;
font-weight: 600;
}
.result-box {
background: var(--vp-c-brand-soft);
border: 2px solid var(--vp-c-brand);
border-radius: 6px;
padding: 0.75rem;
text-align: center;
color: var(--vp-c-brand);
font-weight: 600;
animation: fadeIn 0.3s;
}
@keyframes fadeIn {
from { opacity: 0; transform: scale(0.9); }
to { opacity: 1; transform: scale(1); }
}
.rule-box {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
}
.rule-title {
font-weight: 600;
color: var(--vp-c-text-1);
margin-bottom: 0.5rem;
font-size: 0.85rem;
}
.rule-content {
font-size: 0.85rem;
color: var(--vp-c-text-2);
line-height: 1.5;
}
.rule-content code {
background: var(--vp-c-bg-soft);
padding: 0.1rem 0.3rem;
border-radius: 3px;
font-family: monospace;
}
.function-visual {
display: flex;
flex-direction: column;
align-items: center;
gap: 0.75rem;
}
.global-window {
background: #f5f5f5;
border: 2px solid #e0e0e0;
border-radius: 8px;
padding: 1rem;
width: 100%;
}
.window-title {
font-weight: 600;
color: #666;
margin-bottom: 0.5rem;
font-size: 0.9rem;
}
.window-content {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.global-item {
background: white;
padding: 0.4rem;
border-radius: 4px;
font-size: 0.8rem;
color: #666;
}
.mode-toggle {
display: flex;
flex-direction: column;
align-items: center;
gap: 0.5rem;
}
.toggle-btn {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.5rem 1rem;
border-radius: 6px;
cursor: pointer;
font-size: 0.85rem;
}
.mode-result {
background: var(--vp-c-bg-soft);
padding: 0.5rem;
border-radius: 4px;
font-family: monospace;
color: var(--vp-c-brand);
font-weight: 600;
}
.constructor-process {
display: flex;
flex-direction: column;
align-items: center;
gap: 0.25rem;
}
.process-step {
display: flex;
align-items: center;
gap: 0.5rem;
font-size: 0.85rem;
color: var(--vp-c-text-2);
}
.step-num {
background: var(--vp-c-brand);
color: white;
width: 1.3rem;
height: 1.3rem;
border-radius: 50%;
display: flex;
align-items: center;
justify-content: center;
font-size: 0.7rem;
font-weight: 600;
}
.process-arrow {
color: var(--vp-c-text-3);
font-size: 1rem;
}
.object-comparison {
display: flex;
gap: 1rem;
margin-top: 0.5rem;
}
.obj-instance {
flex: 1;
background: var(--vp-c-bg-soft);
border: 2px solid var(--vp-c-brand);
border-radius: 6px;
padding: 0.5rem;
text-align: center;
}
.obj-title {
font-weight: 600;
color: var(--vp-c-brand);
margin-bottom: 0.25rem;
font-size: 0.85rem;
}
.obj-content {
font-family: monospace;
font-size: 0.8rem;
color: var(--vp-c-text-2);
}
.binding-visual {
display: flex;
flex-direction: column;
align-items: center;
gap: 0.75rem;
}
.function-box {
background: var(--vp-c-bg-soft);
border: 2px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.5rem;
text-align: center;
}
.box-title {
font-weight: 600;
color: var(--vp-c-text-2);
font-size: 0.8rem;
margin-bottom: 0.25rem;
}
.box-content {
font-family: monospace;
font-size: 0.85rem;
color: var(--vp-c-brand);
}
.binding-methods {
display: flex;
gap: 0.5rem;
width: 100%;
}
.binding-item {
flex: 1;
background: var(--vp-c-bg);
border: 2px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.5rem;
text-align: center;
cursor: pointer;
transition: all 0.2s;
}
.binding-item:hover {
border-color: var(--vp-c-brand);
}
.binding-item.active {
border-color: var(--vp-c-brand);
background: var(--vp-c-brand-soft);
}
.method-name {
font-family: monospace;
font-weight: 600;
color: var(--vp-c-text-1);
margin-bottom: 0.25rem;
font-size: 0.8rem;
}
.method-desc {
font-size: 0.7rem;
color: var(--vp-c-text-3);
}
.binding-result {
background: var(--vp-c-brand-soft);
border: 2px solid var(--vp-c-brand);
border-radius: 6px;
padding: 0.75rem;
text-align: center;
color: var(--vp-c-brand);
font-weight: 600;
font-size: 0.9rem;
}
.arrow-function-visual {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.outer-context, .inner-context {
background: var(--vp-c-bg);
border: 2px solid var(--vp-c-brand);
border-radius: 6px;
padding: 0.75rem;
}
.context-title {
font-weight: 600;
color: var(--vp-c-brand);
margin-bottom: 0.5rem;
font-size: 0.85rem;
}
.context-content {
display: flex;
flex-direction: column;
gap: 0.25rem;
}
.context-item {
background: var(--vp-c-bg-soft);
padding: 0.4rem;
border-radius: 4px;
font-family: monospace;
font-size: 0.8rem;
color: var(--vp-c-text-2);
}
.arrow-capture {
text-align: center;
background: var(--vp-c-brand-soft);
padding: 0.5rem;
border-radius: 4px;
}
.capture-title {
font-size: 0.8rem;
color: var(--vp-c-brand);
font-weight: 600;
margin-bottom: 0.25rem;
}
.capture-arrow {
font-size: 0.85rem;
color: var(--vp-c-brand);
}
.quick-reference {
background: var(--vp-c-bg-alt);
border-radius: 6px;
padding: 0.75rem;
margin-top: 1rem;
}
.reference-title {
font-weight: 600;
margin-bottom: 0.5rem;
color: var(--vp-c-text-1);
font-size: 0.9rem;
}
.reference-table {
display: flex;
flex-direction: column;
gap: 0.25rem;
}
.ref-row {
display: flex;
justify-content: space-between;
padding: 0.4rem;
background: var(--vp-c-bg);
border-radius: 4px;
font-size: 0.85rem;
}
.ref-row.header {
background: var(--vp-c-brand-soft);
font-weight: 600;
color: var(--vp-c-brand);
}
.ref-row span:first-child {
font-family: monospace;
}
.info-box {
background: var(--vp-c-bg-alt);
padding: 0.75rem;
border-radius: 6px;
font-size: 0.85rem;
color: var(--vp-c-text-2);
margin-top: 0.75rem;
display: flex;
gap: 0.25rem;
}
.info-box .icon { flex-shrink: 0; }
@media (max-width: 768px) {
.split-view {
grid-template-columns: 1fr;
}
}
</style>
@@ -0,0 +1,366 @@
<template>
<div class="variable-scope-demo">
<div class="demo-header">
<span class="icon">📦</span>
<span class="title">变量与作用域</span>
<span class="subtitle">理解 letconstvar 的区别</span>
</div>
<div class="intro-text">
想象你在<span class="highlight">家里</span><span class="highlight">公司</span>放东西
<span class="highlight">var</span>像是把东西贴在脑门上哪都能看见
<span class="highlight">let</span>像是放在抽屉里当前房间能用
<span class="highlight">const</span>像是焊死在地上的柜子不能移动
</div>
<div class="code-display">
<div class="code-block">
<div class="code-line" v-for="(line, i) in codeLines" :key="i" :class="{ active: currentLine === i }">
<span class="line-num">{{ i + 1 }}</span>
<span class="line-code" v-html="highlightCode(line)"></span>
</div>
</div>
<div class="visualization">
<div class="scope-area global-scope">
<div class="scope-title">全局作用域房子外</div>
<div class="scope-vars">
<div v-if="step >= 1" class="var-item" :class="{ error: step === 4 }">
<span class="var-type">var</span>
<span class="var-name">globalVar</span>
<span class="var-value">= "外面"</span>
</div>
</div>
<div class="scope-area block-scope" v-if="step >= 2">
<div class="scope-title">块级作用域房间内</div>
<div class="scope-vars">
<div v-if="step >= 2" class="var-item" :class="{ error: step === 4 }">
<span class="var-type">var</span>
<span class="var-name">blockVar</span>
<span class="var-value">= "房间里"</span>
</div>
<div v-if="step >= 3" class="var-item let">
<span class="var-type">let</span>
<span class="var-name">blockLet</span>
<span class="var-value">= "只有房间内能用"</span>
</div>
</div>
</div>
</div>
<div class="console-output">
<div class="console-title">控制台输出</div>
<div class="console-lines">
<div v-for="(output, i) in consoleOutput" :key="i" class="console-line" :class="{ error: output.error }">
{{ output.text }}
</div>
</div>
</div>
</div>
</div>
<div class="controls">
<button @click="prevStep" :disabled="step === 0" class="control-btn"> 上一步</button>
<span class="step-indicator">{{ step + 1 }} / {{ maxSteps }}</span>
<button @click="nextStep" :disabled="step === maxSteps" class="control-btn">下一步 </button>
<button @click="reset" class="control-btn secondary">重置</button>
</div>
<div class="info-box">
<span class="icon">💡</span>
<strong>核心思想</strong>
<span v-if="step === 0">var 没有块级作用域"泄漏"到外部let const 有块级作用域只在声明的作用域内有效</span>
<span v-else-if="step === 1">var 声明的变量可以在全局作用域访问容易造成命名冲突</span>
<span v-else-if="step === 2">var 可以重复声明这在大型项目中容易导致难以排查的 bug</span>
<span v-else-if="step === 3">let const 有块级作用域 if 块外部无法访问更安全</span>
<span v-else>const 声明的变量不能重新赋值let 可以推荐优先使用 const需要重新赋值时用 let</span>
</div>
</div>
</template>
<script setup>
import { ref, computed } from 'vue'
const step = ref(0)
const maxSteps = 5
const codeLines = [
'var globalVar = "外面"',
'if (true) {',
' var blockVar = "房间里"',
' let blockLet = "只有房间内能用"',
'}',
'// 尝试访问这些变量'
]
const currentLine = computed(() => {
const lineMap = [0, 1, 2, 3, 1, 4]
return lineMap[step.value]
})
const consoleOutput = ref([])
const scenarios = {
0: { output: [] },
1: { output: [{ text: 'globalVar = "外面"', error: false }] },
2: { output: [{ text: 'globalVar = "外面"', error: false }, { text: 'blockVar = "房间里"', error: false }] },
3: { output: [{ text: 'globalVar = "外面"', error: false }, { text: 'blockVar = "房间里"', error: false }, { text: 'blockLet = "只有房间内能用"', error: false }] },
4: { output: [{ text: 'globalVar = "外面" ✓', error: false }, { text: 'blockVar = "房间里" ✓ (var 泄漏了!)', error: true }, { text: 'blockLet = 报错!let 不在块外部', error: true }] },
5: { output: [{ text: '推荐:const name = "值" (不能改)', error: false }, { text: '需要改:let count = 0 (可以改)', error: false }, { text: '避免:var old = "过时了"', error: true }] }
}
const nextStep = () => {
if (step.value < maxSteps) {
step.value++
consoleOutput.value = scenarios[step.value].output
}
}
const prevStep = () => {
if (step.value > 0) {
step.value--
consoleOutput.value = scenarios[step.value].output
}
}
const reset = () => {
step.value = 0
consoleOutput.value = []
}
const highlightCode = (line) => {
return line
.replace(/(var|let|const)/g, '<span class="keyword">$1</span>')
.replace(/(".+?")/g, '<span class="string">$1</span>')
.replace(/(\/\/.+)/g, '<span class="comment">$1</span>')
}
</script>
<style scoped>
.variable-scope-demo {
border: 1px solid var(--vp-c-divider);
border-radius: 8px;
background: var(--vp-c-bg-soft);
padding: 1rem;
}
.demo-header {
display: flex;
align-items: center;
gap: 0.5rem;
margin-bottom: 0.75rem;
}
.demo-header .icon { font-size: 1.25rem; }
.demo-header .title { font-weight: bold; font-size: 1rem; }
.demo-header .subtitle { color: var(--vp-c-text-2); font-size: 0.85rem; margin-left: 0.5rem; }
.intro-text {
font-size: 0.9rem;
line-height: 1.6;
margin-bottom: 1rem;
color: var(--vp-c-text-1);
}
.highlight {
background: var(--vp-c-brand-soft);
color: var(--vp-c-brand);
padding: 0.1rem 0.3rem;
border-radius: 4px;
font-weight: 500;
}
.code-display {
display: grid;
grid-template-columns: 1fr 1fr;
gap: 1rem;
margin-bottom: 1rem;
}
.code-block {
background: var(--vp-c-bg);
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.75rem;
font-family: 'Monaco', 'Menlo', monospace;
font-size: 0.85rem;
}
.code-line {
display: flex;
gap: 0.5rem;
padding: 0.25rem 0;
border-radius: 4px;
}
.code-line.active {
background: var(--vp-c-brand-soft);
}
.line-num {
color: var(--vp-c-text-3);
min-width: 1.5rem;
text-align: right;
}
.line-code :deep(.keyword) { color: #c586c0; }
.line-code :deep(.string) { color: #ce9178; }
.line-code :deep(.comment) { color: #6a9955; }
.visualization {
display: flex;
flex-direction: column;
gap: 0.75rem;
}
.scope-area {
border: 1px solid var(--vp-c-divider);
border-radius: 6px;
padding: 0.75rem;
background: var(--vp-c-bg);
}
.scope-title {
font-size: 0.85rem;
font-weight: 600;
color: var(--vp-c-text-2);
margin-bottom: 0.5rem;
text-transform: uppercase;
letter-spacing: 0.05em;
}
.scope-vars {
display: flex;
flex-direction: column;
gap: 0.5rem;
}
.var-item {
display: flex;
align-items: center;
gap: 0.5rem;
padding: 0.5rem;
background: var(--vp-c-bg-soft);
border-radius: 4px;
font-size: 0.85rem;
transition: all 0.3s;
}
.var-item.error {
background: #fee;
border: 1px solid #fcc;
}
.var-item.let {
background: #e8f5e9;
border: 1px solid #c8e6c9;
}
.var-type {
background: var(--vp-c-brand);
color: white;
padding: 0.15rem 0.4rem;
border-radius: 3px;
font-size: 0.75rem;
font-weight: 600;
}
.var-name {
font-weight: 600;
color: var(--vp-c-text-1);
}
.var-value {
color: var(--vp-c-text-2);
font-family: monospace;
}
.block-scope {
margin-left: 1rem;
border-left: 3px solid var(--vp-c-brand);
}
.console-output {
background: #1e1e1e;
border-radius: 6px;
padding: 0.75rem;
color: #d4d4d4;
font-family: monospace;
font-size: 0.85rem;
}
.console-title {
font-size: 0.75rem;
color: #888;
margin-bottom: 0.5rem;
text-transform: uppercase;
}
.console-line {
padding: 0.2rem 0;
}
.console-line.error {
color: #f48771;
}
.controls {
display: flex;
justify-content: center;
align-items: center;
gap: 1rem;
margin-top: 1rem;
}
.control-btn {
background: var(--vp-c-brand);
color: white;
border: none;
padding: 0.5rem 1rem;
border-radius: 6px;
cursor: pointer;
font-size: 0.9rem;
transition: opacity 0.2s;
}
.control-btn:hover:not(:disabled) {
opacity: 0.9;
}
.control-btn:disabled {
opacity: 0.5;
cursor: not-allowed;
}
.control-btn.secondary {
background: transparent;
border: 1px solid var(--vp-c-divider);
color: var(--vp-c-text-1);
}
.step-indicator {
font-size: 0.9rem;
color: var(--vp-c-text-2);
font-weight: 500;
}
.info-box {
background: var(--vp-c-bg-alt);
padding: 0.75rem;
border-radius: 6px;
font-size: 0.85rem;
color: var(--vp-c-text-2);
margin-top: 0.75rem;
display: flex;
gap: 0.25rem;
}
.info-box .icon { flex-shrink: 0; }
@media (max-width: 768px) {
.code-display {
grid-template-columns: 1fr;
}
}
</style>