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class="content-wrap"><div id="content" class="content"><div id="posts" class="posts-expand"><article class="post post-type-normal" itemscope itemtype="http://schema.org/Article"><div class="post-block"><link itemprop="mainEntityOfPage" href="https://www.jealyn.top/jsexer13-ans.html"><span hidden itemprop="author" itemscope itemtype="http://schema.org/Person"><meta itemprop="name" content="jealyn.wang"><meta itemprop="description" content="前端小白一枚"><meta itemprop="image" content="/images/avatar.png"></span><span hidden itemprop="publisher" itemscope itemtype="http://schema.org/Organization"><meta itemprop="name" content="Jealyn的个人网站"></span><header class="post-header"><h2 class="post-title" itemprop="name headline">js练习题第13天 答案及解析</h2><div class="post-meta"><span class="post-time"><span class="post-meta-item-icon"><i class="fa fa-calendar-o"></i> </span><span class="post-meta-item-text"></span> <time title="创建于" itemprop="dateCreated datePublished" datetime="2019-03-28T20:52:28+08:00">2019-03-28 </time></span><span class="post-category"><span class="post-meta-divider">|</span> <span class="post-meta-item-icon"><i class="fa fa-folder-o"></i> </span><span class="post-meta-item-text"></span> <span itemprop="about" itemscope itemtype="http://schema.org/Thing"><a href="/categories/JS基础练习题/" itemprop="url" rel="index"><span itemprop="name">JS基础练习题</span> </a></span>， <span itemprop="about" itemscope itemtype="http://schema.org/Thing"><a href="/categories/JS基础练习题/答案及解析/" itemprop="url" rel="index"><span itemprop="name">答案及解析</span> </a></span></span><span class="post-meta-divider">|</span> <span class="page-pv"><i class="fa fa-eye"></i> 阅读数 <span class="busuanzi-value" id="busuanzi_value_page_pv"></span>次</span><div class="post-wordcount"><span class="post-meta-item-icon"><i class="fa fa-file-word-o"></i> </span><span class="post-meta-item-text">字数统计:</span> <span title="字数统计">865 字 </span><span class="post-meta-divider">|</span> <span class="post-meta-item-icon"><i class="fa fa-clock-o"></i> </span><span class="post-meta-item-text">阅读时长 ≈</span> <span title="阅读时长">3 分钟</span></div></div></header><div class="post-body" itemprop="articleBody"><blockquote><p>本篇文章是js基础练习题第十三天的答案及解析部分，纯题目部分请移步<a href="/jsexer13.html" title="js基础练习题 第13天">js基础练习题 第13天</a></p></blockquote><a id="more"></a><h2 id="正文"><a href="#正文" class="headerlink" title="正文"></a>正文</h2><p>1.js有几种基本数据类型？<br></p><div class="note info"><h3>答案：在js中一共有7种基本数据类型，分别是<code>number</code>, <code>string</code>, <code>boolean</code>, <code>null</code>, <code>undefined</code>, <code>symbol</code>, <code>bigint</code></h3></div><div class="note warning"><p>关于<code>symbol</code>的介绍，可以参照<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Symbol" target="_blank" rel="noopener">MDN symbol</a>，关于<code>bigint</code>的介绍，可以参看<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/BigInt" target="_blank" rel="noopener">MDN bigint</a></p></div><br>2.js有几种引用数据类型？<div class="note info"><h3>答案：在js中一共有3种引用数据类型，分别是<code>object</code>、<code>array</code>、<code>function</code></h3></div><br>3.简述基本数据类型与引用数据类型的区别。<br><div class="note info"><h3>从数据存储上来说，基本数据类型的名（key）和值（value）都存储在栈内存中；而引用数据类型的名存在栈内存中，值存在于堆内存中，栈内存会提供一个引用的地址（指针）指向堆内存中的值。</h3></div><br>4.深拷贝与浅拷贝有何区别？如何利用js实现一个简单的深拷贝，试给出你的代码。<div class="note info"><p></p><h3>浅拷贝是对栈内存中的值（即指针）的拷贝，拷贝前后对象指向的是堆内存中的同一个值；深拷贝是指在堆内存中开辟一个新的内存专门来存放拷贝值，此时拷贝后的值与原值就是相互独立、互不影响的。</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br></pre></td><td class="code"><pre><span class="line"><span class="comment">// 可以使用递归去复制所有层级属性</span></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">deepClone</span>(<span class="params">obj</span>) </span>{</span><br><span class="line"> <span class="keyword">let</span> objClone = <span class="built_in">Array</span>.isArray(obj) ? [] : {};</span><br><span class="line"> <span class="keyword">if</span>(obj && <span class="keyword">typeof</span> obj === <span class="string">“object”</span>) {</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">var</span> key <span class="keyword">in</span> obj) {</span><br><span class="line"> <span class="keyword">if</span>(obj.hasOwnProperty(key)) {</span><br><span class="line"> <span class="comment">//判断ojb子元素是否为对象，如果是，递归复制</span></span><br><span class="line"> <span class="keyword">if</span>(obj[key] && <span class="keyword">typeof</span> obj[key] === <span class="string">“object”</span>) {</span><br><span class="line"> objClone[key] = deepClone(obj[key]);</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="comment">//如果不是，简单复制</span></span><br><span class="line"> objClone[key] = obj[key];</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="keyword">return</span> obj;</span><br><span class="line"> } </span><br><span class="line"> <span class="keyword">return</span> objClone;</span><br><span class="line">} </span><br></pre></td></tr></table></figure><p></p></div><div class="note warning"><p>使用复制代码时，请将代码中的中文双引号替换为英文引号。</p></div><br>5.<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> a = <span class="number">10</span>;</span><br><span class="line"><span class="keyword">var</span> b = <span class="number">20</span>;</span><br><span class="line"><span class="keyword">var</span> obj = {</span><br><span class="line"> a: <span class="number">30</span>,</span><br><span class="line"> b: <span class="keyword">this</span>.a + <span class="number">40</span>,</span><br><span class="line"> foo: <span class="function"><span class="keyword">function</span> (<span class="params"></span>) </span>{ </span><br><span class="line"> <span class="keyword">return</span> <span class="keyword">this</span>.a; </span><br><span class="line"> },</span><br><span class="line"> bar: <span class="function"><span class="params">()</span> =></span> <span class="keyword">this</span>.a ,</span><br><span class="line"> baz: <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{ </span><br><span class="line"> <span class="function"><span class="keyword">function</span> <span class="title">abc</span>(<span class="params"></span>) </span>{ </span><br><span class="line"> <span class="keyword">return</span> <span class="keyword">this</span>.b;</span><br><span class="line"> } </span><br><span class="line"> abc(); </span><br><span class="line"> },</span><br><span class="line">}</span><br></pre></td></tr></table></figure>以上代码运行后，则<code>obj.b</code> = __________，<code>obj.foo()</code>的返回值为 __________，<div class="note info"><h3>答案：50、30</h3></div>执行了<figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> test = obj.foo;</span><br></pre></td></tr></table></figure>后，<code>test()</code>的返回值为__________，<code>obj.bar()</code>的返回值为__________，<code>obj.baz()</code>的返回值为__________。<div class="note info"><h3>答案：10、10、undefined</h3></div><div class="note warning"><p>关于js中<code>this</code>的讲解，可以参照<a href="https://www.jianshu.com/p/d647aa6d1ae6" target="_blank" rel="noopener">这波能反杀的个人博客</a>。</p></div><br>6.实现一个add方法，使计算结果能够满足如下预期：<br><code>add(1, 2, 3) = 6</code><br><code>add(1, 2, 3)(4) = 10</code><br><code>add(1)(2)(3)(4)(5) = 15</code><div class="note info"><p></p><h3>答案：如下方代码段所示</h3><figure class="highlight javascript"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> add = <span class="function">(<span class="params">…args</span>) =></span> { </span><br><span class="line"> <span class="keyword">const</span> _add = <span class="function"><span class="keyword">function</span>(<span class="params"></span>) </span>{ </span><br><span class="line"> args.push(…arguments); </span><br><span class="line"> <span class="keyword">return</span> _add;</span><br><span class="line"> }</span><br><span class="line"> _add.toString = <span class="function"><span class="params">()</span> =></span> {</span><br><span class="line"> <span class="keyword">return</span> args.reduce( <span class="function">(<span class="params">a, b</span>) =></span> a + b );</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> _add;</span><br><span class="line">}</span><br></pre></td></tr></table></figure><p></p></div><br>7.说说你了解的<code>Promise</code>。<br><div class="note info"><h3><code>Promise</code>是一种异步机制，主要是用来解决回调地狱的问题。<code>Promise</code>对象有三种状态，分别是<code>pending</code>、<code>resolved</code>、<code>rejected</code>；在<code>Promise</code>对象的构造函数中，接收<code>resolve</code>和<code>reject</code>函数修改状态；<code>Promise</code>对象中的<code>then</code>方法，可以接收构造函数中处理的状态变化，并分别对应执行。<code>then</code>方法的执行结果也会返回一个<code>Promise</code>对象，因此可以进行<code>then</code>的链式执行，这也是解决回调地狱的主要方式。</h3></div><p></p><h2 id="说明"><a href="#说明" class="headerlink" title="说明"></a>说明</h2><ol><li>题目中出现的JS指的是采用ECMAScript 2015及之后标准的JavaScript</li></ol><ol start="2"><li><p>答案中，若有错误和需完善的地方，可在下方留言反馈哈~~</p></li><li><p>查看纯习题版，请点击<a href="/jsexer13.html" title="js基础练习题 第13天">js基础练习题 第13天</a></p></li></ol></div><div><div><div style="text-align:center;color:#ccc;font-size:14px;letter-spacing:.2rem">--本文结束 <i class="fa fa-heart"></i> 感谢阅读--</div></div></div><div><div style="padding:10px 0;margin:20px auto;width:90%;text-align:center"><div>创作十分不易，原创更应鼓励</div><button id="rewardButton" disable="enable" 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class="nav-text">从数据存储上来说，基本数据类型的名（key）和值（value）都存储在栈内存中；而引用数据类型的名存在栈内存中，值存在于堆内存中，栈内存会提供一个引用的地址（指针）指向堆内存中的值。</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#undefined"><span class="nav-number">1.4.</span> <span class="nav-text">浅拷贝是对栈内存中的值（即指针）的拷贝，拷贝前后对象指向的是堆内存中的同一个值；深拷贝是指在堆内存中开辟一个新的内存专门来存放拷贝值，此时拷贝后的值与原值就是相互独立、互不影响的。</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#undefined"><span class="nav-number">1.5.</span> <span class="nav-text">答案：50、30</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#undefined"><span class="nav-number">1.6.</span> <span class="nav-text">答案：10、10、undefined</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#undefined"><span class="nav-number">1.7.</span> <span class="nav-text">答案：如下方代码段所示</span></a></li><li class="nav-item nav-level-3"><a class="nav-link" href="#undefined"><span class="nav-number">1.8.</span> <span class="nav-text">Promise是一种异步机制，主要是用来解决回调地狱的问题。Promise对象有三种状态，分别是pending、resolved、rejected；在Promise对象的构造函数中，接收resolve和reject函数修改状态；Promise对象中的then方法，可以接收构造函数中处理的状态变化，并分别对应执行。then方法的执行结果也会返回一个Promise对象，因此可以进行then的链式执行，这也是解决回调地狱的主要方式。</span></a></li></ol></li><li class="nav-item nav-level-2"><a class="nav-link" href="#说明"><span class="nav-number">2.</span> <span class="nav-text">说明</span></a></li></ol></div></div></section></div></aside></div></main><footer id="footer" class="footer"><div class="footer-inner"><div class="copyright">© <span itemprop="copyrightYear">2019</span> <span class="with-love"><i class="fa fa-user"></i> </span><span class="author" itemprop="copyrightHolder">jealyn.wang</span></div><div class="busuanzi-count"><script async src="https://busuanzi.ibruce.info/busuanzi/2.3/busuanzi.pure.mini.js"></script><span class="site-uv">访客数 <i class="fa fa-user"></i> <span class="busuanzi-value" id="busuanzi_value_site_uv"></span> 人 </span><span class="site-pv">浏览数 <i class="fa 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