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Puppeteer 多 iframe 场景表单代填
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<p><a name="DqBmD"></a></p>
<h1 id="一、初始化"><a href="#一、初始化" class="headerlink" title="一、初始化"></a>一、初始化</h1><p>创建一个用来测试的目录，然后安装 puppeteer 依赖项<br><figure class="highlight bash"><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></pre></td><td class="code"><pre><span class="line">mkdir puppeteer-auto-fill</span><br><span class="line"><span class="built_in">cd</span> puppeteer-auto-fill</span><br><span class="line">npm init</span><br><span class="line">npm i puppeteer</span><br></pre></td></tr></table></figure></p>
<p>创建一个 <code>index.js</code> 文件用来编写测试脚本。往<code>package.json</code>中添加<code>scripts</code>：<br><figure class="highlight"><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></pre></td><td class="code"><pre><span class="line">"scripts": {</span><br><span class="line"> "start": "node index.js",</span><br><span class="line"> "debug": "env DEBUG=\"puppeteer:*\" node --inspect-brk index.js"</span><br><span class="line">},</span><br></pre></td></tr></table></figure></p>
<blockquote>
<p>Chrome DevTool 调试方式：</p>
<ol>
<li>打开 Chrome，输入 chrome://inspect/#devices</li>
<li>运行 <code>debug</code> 脚本后，可以看到调试页面，点击 <code>inpect</code> 进入断点调试<img src="https://cdn.nlark.com/yuque/0/2021/png/21653038/1622184584922-9fd841c8-a6ea-47c1-85f8-37be2d2b8246.png#clientId=u9d8a5b67-f968-4&from=paste&height=720&id=u6e90bc88&margin=%5Bobject%20Object%5D&name=image.png&originHeight=720&originWidth=1670&originalType=binary&size=106944&status=done&style=none&taskId=u811bd462-7333-46df-afd4-aa360321338&width=1670" alt="image.png"></li>
</ol>
</blockquote>
<p><a name="ZeqSj"></a></p>
<h1 id="二、代填逻辑"><a href="#二、代填逻辑" class="headerlink" title="二、代填逻辑"></a>二、代填逻辑</h1><p><a name="uwQGi"></a></p>
<h2 id="1-模拟多-iframe-嵌套场景"><a href="#1-模拟多-iframe-嵌套场景" class="headerlink" title="1. 模拟多 iframe 嵌套场景"></a>1. 模拟多 iframe 嵌套场景</h2><p>iframe嵌套关系如下：<br></p>
<p><img src="https://cdn.nlark.com/yuque/0/2021/jpeg/21653038/1622185048680-c13ed665-7509-4391-b489-f86f5f26530a.jpeg" alt=""><a name="JJq3M"></a></p>
<h2 id="2-代填脚本"><a href="#2-代填脚本" class="headerlink" title="2. 代填脚本"></a>2. 代填脚本</h2><ul>
<li>启动参数说明：</li>
</ul>
<p><code>headless: false</code> 是否在后台进行<br><code>devtools: true</code> 打开页面后是否显示开发者工具<br><code>slowMo: 0</code> 操作延时，把这个数字可以调大相当于慢放</p>
<ul>
<li><code>Frame</code> 查找：<br>通过 <code>Frame.$(.selector)</code> 的方式查找返回选择器条件的 iframe，如果找不到会返回 <code>null</code>，否则会返回一个 <code>ElementHandle</code> 对象，然后在通过 <code>.contentFrame()</code> 将其转换为 <code>Frame</code> 对象。</li>
<li><code>Page</code> 和 <code>Frame</code> 都有 <code>.waitForSelector()</code> 方式用于等待元素加载完成。</li>
<li>通过 <code>.waitForTimeout()</code> 方法来实现延时输入效果。</li>
</ul>
<p></p>
<p>完整代码如下：<br><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><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br><span class="line">35</span><br><span class="line">36</span><br><span class="line">37</span><br><span class="line">38</span><br><span class="line">39</span><br><span class="line">40</span><br><span class="line">41</span><br><span class="line">42</span><br><span class="line">43</span><br><span class="line">44</span><br><span class="line">45</span><br><span class="line">46</span><br><span class="line">47</span><br><span class="line">48</span><br><span class="line">49</span><br><span class="line">50</span><br><span class="line">51</span><br><span class="line">52</span><br><span class="line">53</span><br><span class="line">54</span><br><span class="line">55</span><br><span class="line">56</span><br><span class="line">57</span><br><span class="line">58</span><br><span class="line">59</span><br><span class="line">60</span><br><span class="line">61</span><br><span class="line">62</span><br><span class="line">63</span><br><span class="line">64</span><br><span class="line">65</span><br><span class="line">66</span><br><span class="line">67</span><br><span class="line">68</span><br><span class="line">69</span><br><span class="line">70</span><br><span class="line">71</span><br><span class="line">72</span><br><span class="line">73</span><br><span class="line">74</span><br><span class="line">75</span><br><span class="line">76</span><br><span class="line">77</span><br><span class="line">78</span><br><span class="line">79</span><br><span class="line">80</span><br><span class="line">81</span><br><span class="line">82</span><br><span class="line">83</span><br><span class="line">84</span><br><span class="line">85</span><br><span class="line">86</span><br><span class="line">87</span><br><span class="line">88</span><br><span class="line">89</span><br><span class="line">90</span><br><span class="line">91</span><br><span class="line">92</span><br><span class="line">93</span><br><span class="line">94</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> puppeteer = <span class="built_in">require</span>(<span class="string">'puppeteer'</span>);</span><br><span class="line"></span><br><span class="line">(<span class="keyword">async</span> () => {</span><br><span class="line"> <span class="keyword">const</span> browser = <span class="keyword">await</span> puppeteer.launch({ <span class="attr">headless</span>: <span class="literal">false</span>, <span class="attr">devtools</span>: <span class="literal">true</span>, <span class="attr">slowMo</span>: <span class="number">0</span> });</span><br><span class="line"> <span class="keyword">const</span> page = <span class="keyword">await</span> browser.newPage();</span><br><span class="line"> <span class="keyword">await</span> page.goto(<span class="string">'http://localhost/frameset/index.html'</span>);</span><br><span class="line"> tryFillForm(page, [</span><br><span class="line"> { <span class="attr">type</span>: <span class="string">'iframe'</span>, <span class="attr">selector</span>: <span class="string">'#app > iframe:nth-child(3)'</span> },</span><br><span class="line"> { <span class="attr">type</span>: <span class="string">'iframe'</span>, <span class="attr">selector</span>: <span class="string">'body > iframe'</span> },</span><br><span class="line"> { <span class="attr">type</span>: <span class="string">'text'</span>, <span class="attr">selector</span>: <span class="string">'#login'</span>, <span class="attr">value</span>: <span class="string">'admin'</span> },</span><br><span class="line"> { <span class="attr">type</span>: <span class="string">'password'</span>, <span class="attr">selector</span>: <span class="string">'#pwd'</span>, <span class="attr">value</span>: <span class="string">'12345678'</span> },</span><br><span class="line"> ]);</span><br><span class="line">})();</span><br><span class="line"></span><br><span class="line"></span><br><span class="line"><span class="keyword">let</span> tryFillForm = <span class="keyword">async</span> <span class="function"><span class="keyword">function</span>(<span class="params">page, autoFillInfo</span>) </span>{</span><br><span class="line"> <span class="keyword">try</span> {</span><br><span class="line"> <span class="keyword">await</span> page.evaluateOnNewDocument(<span class="function"><span class="params">()</span> =></span> {</span><br><span class="line"> <span class="built_in">Object</span>.defineProperty(navigator, <span class="string">'webdriver'</span>, {</span><br><span class="line"> get: <span class="function"><span class="params">()</span> =></span> <span class="literal">false</span>,</span><br><span class="line"> });</span><br><span class="line"> });</span><br><span class="line"> <span class="keyword">let</span> waitEntry = page;</span><br><span class="line"> <span class="keyword">let</span> frameDeep = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i < autoFillInfo.length; i++) {</span><br><span class="line"> <span class="keyword">let</span> info = autoFillInfo[i];</span><br><span class="line"> <span class="keyword">if</span>(<span class="string">'iframe'</span> === info.type) {</span><br><span class="line"> <span class="keyword">await</span> waitEntry.waitForSelector(info.selector, {<span class="attr">timeout</span> : <span class="number">5000</span>});</span><br><span class="line"> <span class="keyword">let</span> iframe = <span class="literal">null</span>;</span><br><span class="line"> <span class="keyword">if</span>(frameDeep === <span class="number">0</span>) {</span><br><span class="line"> iframe = <span class="keyword">await</span> waitEntry.mainFrame().$(info.selector);</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> iframe = <span class="keyword">await</span> waitEntry.$(info.selector);</span><br><span class="line"> }</span><br><span class="line"> <span class="comment">//frames.forEach(f=>console.log(f.name()));</span></span><br><span class="line"> <span class="keyword">if</span> (iframe) {</span><br><span class="line"> <span class="comment">//console.log(iframe.url());</span></span><br><span class="line"> waitEntry = <span class="keyword">await</span> iframe.contentFrame();</span><br><span class="line"> }</span><br><span class="line"> <span class="comment">// break;</span></span><br><span class="line"> frameDeep++;</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i < autoFillInfo.length; i++) {</span><br><span class="line"> <span class="keyword">let</span> info = autoFillInfo[i];</span><br><span class="line"> <span class="keyword">if</span>(<span class="string">'iframe'</span> !== info.type) {</span><br><span class="line"> <span class="keyword">await</span> waitEntry.waitForSelector(info.selector, {<span class="attr">timeout</span> : <span class="number">120000</span>});</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">for</span>(<span class="keyword">let</span> i = <span class="number">0</span>; i < autoFillInfo.length; i++) {</span><br><span class="line"> <span class="keyword">let</span> info = autoFillInfo[i];</span><br><span class="line"> <span class="keyword">let</span> type = info.type;</span><br><span class="line"> <span class="keyword">if</span>(<span class="string">'iframe'</span> !== type) {</span><br><span class="line"> <span class="keyword">if</span>(!type) {</span><br><span class="line"> type = <span class="keyword">await</span> waitEntry.evaluate(<span class="function">(<span class="params">selector</span>) =></span> {</span><br><span class="line"> <span class="keyword">let</span> element = <span class="built_in">document</span>.querySelector(selector);</span><br><span class="line"> <span class="keyword">if</span>(element) {</span><br><span class="line"> <span class="keyword">let</span> nodeName = element.nodeName.toLowerCase();</span><br><span class="line"> <span class="keyword">let</span> type = nodeName;</span><br><span class="line"> <span class="keyword">if</span>(nodeName === <span class="string">'input'</span>) {</span><br><span class="line"> type = element.type || <span class="string">'text'</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(type === <span class="string">'submit'</span>) {</span><br><span class="line"> type = <span class="string">'button'</span>;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> type;</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">return</span> <span class="literal">null</span>;</span><br><span class="line"> }, info.selector);</span><br><span class="line"> }</span><br><span class="line"> <span class="keyword">if</span>(type) {</span><br><span class="line"> <span class="built_in">console</span>.log(info);</span><br><span class="line"> <span class="keyword">if</span>(type === <span class="string">'text'</span> || type === <span class="string">'password'</span>) {<span class="comment">//填充节点</span></span><br><span class="line"> <span class="comment">//有些节点必须通过type来改变值，有些节点只能直接改变value，所以两个都做，先type然后再改值</span></span><br><span class="line"> <span class="keyword">await</span> waitEntry.type(info.selector, info.value);</span><br><span class="line"> <span class="keyword">await</span> waitEntry.evaluate(<span class="function">(<span class="params">data</span>) =></span> {</span><br><span class="line"> <span class="keyword">return</span> <span class="built_in">document</span>.querySelector(data.selector).value = data.value</span><br><span class="line"> }, info);</span><br><span class="line"> <span class="comment">// 等待 0.5s</span></span><br><span class="line"> <span class="keyword">await</span> waitEntry.waitForTimeout(<span class="number">500</span>);</span><br><span class="line"> } <span class="keyword">else</span> <span class="keyword">if</span>(type == <span class="string">'select'</span>) {<span class="comment">//combbox</span></span><br><span class="line"> <span class="keyword">await</span> waitEntry.select(info.selector, info.value);</span><br><span class="line"> } <span class="keyword">else</span> <span class="keyword">if</span>(type == <span class="string">'button'</span>) {</span><br><span class="line"> waitEntry.click(info.selector, {<span class="attr">delay</span> : <span class="number">1000</span>});</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> waitEntry.click(info.selector);</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> }</span><br><span class="line"> } <span class="keyword">catch</span>(e) {</span><br><span class="line"> <span class="built_in">console</span>.error(e);</span><br><span class="line"> }</span><br><span class="line">};</span><br></pre></td></tr></table></figure></p>
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Narrowing 类型收缩 - 《TypeScript学习笔记》
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<h1 id="type-guards-类型守卫-和-narrowing"><a href="#type-guards-类型守卫-和-narrowing" class="headerlink" title="type guards (类型守卫) 和 narrowing"></a>type guards (类型守卫) 和 narrowing</h1><p>通过 <code>if</code> 条件语句对类型进行判断，TypeScript会对变量的类型进行分析，以明白这个分支下变量的具体类型，这个过程叫做 <code>type guards</code> 。而这整个由不确定类型到确定具体类型到过程就叫做 <code>narrowing</code> ，下面有几种方式可以对类型进行校验。</p>
<h1 id="typeof-守卫"><a href="#typeof-守卫" class="headerlink" title="typeof 守卫"></a><code>typeof</code> 守卫</h1><p>可以通过 <code>typeofe</code> 运算符对类型进行最基础对判断：</p>
<ul>
<li><code>string</code></li>
<li><code>number</code></li>
<li><code>bigint</code></li>
<li><code>boolean</code></li>
<li><code>symbol</code></li>
<li><code>undefined</code></li>
<li><code>object</code></li>
<li><code>function</code></li>
</ul>
<h1 id="Truthiness-narrowing（是否为真）"><a href="#Truthiness-narrowing（是否为真）" class="headerlink" title="Truthiness narrowing（是否为真）"></a>Truthiness narrowing（是否为真）</h1><p>在 <code>if</code> 表达式内，JavaScript 对条件是否为真对判断并不是决定对，它会把非 <code>boolean</code> 类型对表达式转化为 <code>boolean</code> 类型进行判断。下面的值会被转化为 <code>false</code> ：</p>
<ul>
<li><code>0</code></li>
<li><code>NaN</code></li>
<li><code>""</code>（空字符串）</li>
<li><code>0n</code> （大整型0）</li>
<li><code>null</code></li>
<li><code>undefined</code></li>
</ul>
<p>除了上面这些值会被转化为<code>false</code>，其它都会被转发为<code>true</code>。</p>
<h1 id="Equality-narrowing（是否相等）"><a href="#Equality-narrowing（是否相等）" class="headerlink" title="Equality narrowing（是否相等）"></a>Equality narrowing（是否相等）</h1><p>我们可以通过 <code>===</code>，<code>!==</code>，<code>==</code>，<code>!=</code> 对类型进行收缩。比如：<br><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></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">example</span>(<span class="params">x: string | number, y: string | boolean</span>) </span>{</span><br><span class="line"> <span class="keyword">if</span> (x === y) {</span><br><span class="line"> <span class="comment">// We can now call any 'string' method on 'x' or 'y'.</span></span><br><span class="line"> x.toUpperCase();</span><br><span class="line"> <span class="comment">// ^?</span></span><br><span class="line"> y.toLowerCase();</span><br><span class="line"> <span class="comment">// ^?</span></span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="built_in">console</span>.log(x);</span><br><span class="line"> <span class="comment">// ^?</span></span><br><span class="line"> <span class="built_in">console</span>.log(y);</span><br><span class="line"> <span class="comment">// ^?</span></span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
<h1 id="instanceof-narrowing（原型校验）"><a href="#instanceof-narrowing（原型校验）" class="headerlink" title="instanceof narrowing（原型校验）"></a><code>instanceof</code> narrowing（原型校验）</h1><p>这种方式用来检查通过<code>new</code>对方式创建出来对对象对类型。<br><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></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">logValue</span>(<span class="params">x: Date | string</span>) </span>{</span><br><span class="line"> <span class="keyword">if</span> (x <span class="keyword">instanceof</span> <span class="built_in">Date</span>) {</span><br><span class="line"> <span class="built_in">console</span>.log(x.toUTCString());</span><br><span class="line"> } <span class="keyword">else</span> {</span><br><span class="line"> <span class="built_in">console</span>.log(x.toUpperCase());</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
<h1 id="赋值操作"><a href="#赋值操作" class="headerlink" title="赋值操作"></a>赋值操作</h1><p>TypeScript会根据赋值操作符<code>=</code>右边对类型决定变量的类型<br><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">let</span> x = <span class="built_in">Math</span>.random() < <span class="number">0.5</span> ? <span class="number">10</span> : <span class="string">"hello world!"</span>;</span><br></pre></td></tr></table></figure></p>
<p>这里的 <code>x</code> 会被推断为 <code>string | number</code> 两种类型。</p>
<h1 id="类型断言"><a href="#类型断言" class="headerlink" title="类型断言"></a>类型断言</h1><p>对于自定义类型，可以通过 <code>parameterName is Type</code> 的方式断言某个变量是 <code>Type</code> 类型，其中 <code>parameterName</code> 必须为函数的参数<br><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></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">isFish</span>(<span class="params">pet: Fish | Bird</span>): <span class="title">pet</span> <span class="title">is</span> <span class="title">Fish</span> </span>{</span><br><span class="line"> <span class="keyword">return</span> (pet <span class="keyword">as</span> Fish).swim !== <span class="literal">undefined</span>;</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
<h1 id="联合类型"><a href="#联合类型" class="headerlink" title="联合类型"></a>联合类型</h1><p>通过 <code>|</code> 符号来表示字面类型的组合，如：<br><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></pre></td><td class="code"><pre><span class="line">interface Shape {</span><br><span class="line"> kind: <span class="string">"circle"</span> | <span class="string">"square"</span>;</span><br><span class="line"> radius?: number;</span><br><span class="line"> sideLength?: number;</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
<h1 id="never-类型"><a href="#never-类型" class="headerlink" title="never 类型"></a><code>never</code> 类型</h1><p><code>never</code> 类型表示一个不应该存在的状态，如：<br><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></pre></td><td class="code"><pre><span class="line">type Shape = Circle | Square;</span><br><span class="line"></span><br><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">getArea</span>(<span class="params">shape: Shape</span>) </span>{</span><br><span class="line"> <span class="keyword">switch</span> (shape.kind) {</span><br><span class="line"> <span class="keyword">case</span> <span class="string">"circle"</span>:</span><br><span class="line"> <span class="keyword">return</span> <span class="built_in">Math</span>.PI * shape.radius ** <span class="number">2</span>;</span><br><span class="line"> <span class="keyword">case</span> <span class="string">"square"</span>:</span><br><span class="line"> <span class="keyword">return</span> shape.sideLength ** <span class="number">2</span>;</span><br><span class="line"> <span class="keyword">default</span>:</span><br><span class="line"> <span class="keyword">const</span> _exhaustiveCheck: never = shape;</span><br><span class="line"> <span class="keyword">return</span> _exhaustiveCheck;</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
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Nginx 配置虚拟主机
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<p>本文记录了在 Mac OSX 下，通过 Nginx 1.15.5 来配置虚拟主机的过程。</p>
<h1 id="0-准备工作"><a href="#0-准备工作" class="headerlink" title="0. 准备工作"></a>0. 准备工作</h1><p>本次模拟的是效果是，通过浏览器访问 <a href="http://www.shop.com" target="_blank" rel="noopener">www.shop.com</a> 和 api.shop.com 能定位到不同的网站目录下：</p>
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<li><a href="http://www.shop.com" target="_blank" rel="noopener">www.shop.com</a> -> ~/Sites/home</li>
<li>api.show.com -> ~/Sites/api</li>
</ul>
<p>上面的两个域名是随便取的，为了能让它指向本地，我们需要修改 <code>vhost</code> 文件：<br><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo vim /private/etc/hosts</span><br></pre></td></tr></table></figure></p>
<p>追加：<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br></pre></td><td class="code"><pre><span class="line">127.0.0.1 www.shop.com</span><br><span class="line">127.0.0.1 api.shop.com</span><br></pre></td></tr></table></figure></p>
<h1 id="1-通过-brew-安装-nginx"><a href="#1-通过-brew-安装-nginx" class="headerlink" title="1. 通过 brew 安装 nginx"></a>1. 通过 brew 安装 nginx</h1><p>通过 homebrew 安装 nginx:<br><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">brew install nginx</span><br></pre></td></tr></table></figure></p>
<p>安装完成后通过 <code>brew services start nginx</code> 启动 nginx 服务</p>
<h1 id="2-修改-nginx-配置文件"><a href="#2-修改-nginx-配置文件" class="headerlink" title="2. 修改 nginx 配置文件"></a>2. 修改 nginx 配置文件</h1><p>接下来需要对 nginx 的配置文件(<code>/usr/local/etc/nginx/nginx.conf</code>)进行修改，打开 <code>nginx.conf</code> 确保下面这行配置已经启用：<br><figure class="highlight plain"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">include servers/*;</span><br></pre></td></tr></table></figure></p>
<h1 id="3-添加虚拟主机配置文件"><a href="#3-添加虚拟主机配置文件" class="headerlink" title="3. 添加虚拟主机配置文件"></a>3. 添加虚拟主机配置文件</h1><p>然后，在 <code>/usr/local/etc/nginx/services</code> 目录下，创建两个配置文件（<code>home.conf, api.conf</code>）用于对上面两个 host 进行配置<br><figure class="highlight plain"><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><span class="line">21</span><br></pre></td><td class="code"><pre><span class="line"># home.conf</span><br><span class="line">server {</span><br><span class="line"> listen 80;</span><br><span class="line"> server_name www.shop.com;</span><br><span class="line"></span><br><span class="line"> location / {</span><br><span class="line"> root /Users/mcbird/Sites/main;</span><br><span class="line"> index index.html index.htm;</span><br><span class="line"> }</span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"># api.conf</span><br><span class="line">server {</span><br><span class="line"> listen 80;</span><br><span class="line"> server_name api.shop.com;</span><br><span class="line"></span><br><span class="line"> location / {</span><br><span class="line"> root /Users/mcbird/Sites/api;</span><br><span class="line"> index index.html index.htm;</span><br><span class="line"> }</span><br><span class="line">}</span><br></pre></td></tr></table></figure></p>
<h1 id="4-加载新的-nginx-配置"><a href="#4-加载新的-nginx-配置" class="headerlink" title="4. 加载新的 nginx 配置"></a>4. 加载新的 nginx 配置</h1><p>修改完 nginx 配置文件，并不会立即生效，接下来可以先对配置文件进行检查：<br><figure class="highlight bash"><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></pre></td><td class="code"><pre><span class="line"><span class="comment"># 检查配置文件是否有语法错误</span></span><br><span class="line">sudo nginx -t</span><br><span class="line">nginx: the configuration file /usr/<span class="built_in">local</span>/etc/nginx/nginx.conf syntax is ok</span><br><span class="line">nginx: configuration file /usr/<span class="built_in">local</span>/etc/nginx/nginx.conf <span class="built_in">test</span> is successful</span><br></pre></td></tr></table></figure></p>
<p>检查成功后，通过 <code>reload</code> 信号重新加载配置文件：<br><figure class="highlight bash"><table><tr><td class="gutter"><pre><span class="line">1</span><br></pre></td><td class="code"><pre><span class="line">sudo nginx -s reload</span><br></pre></td></tr></table></figure></p>
<h1 id="5-完成"><a href="#5-完成" class="headerlink" title="5. 完成"></a>5. 完成</h1><p>通过浏览器访问 <a href="http://www.shop.com" target="_blank" rel="noopener">www.shop.com</a> 就会打开 <code>/Users/mcbird/Sites/main/index.html</code> 文件；api.shop.com 会打开 <code>/Users/mcbird/Sites/api/index.html</code></p>
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Webpack 是如何加载模块的
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<p>Webpack 在前端开发中作为模块打包工具非常受开发者的青睐，丰富的 loader 使它可以实现各种各样的功能。本文将通过 webpack 来打包一个 js 文件，看看 webpack 是如何加载各个模块的。</p>
<h1 id="两个简单的源文件"><a href="#两个简单的源文件" class="headerlink" title="两个简单的源文件"></a>两个简单的源文件</h1><p>为了方便分析 webpack 加载模块的原理，我们准备了两个文件：</p>
<p>hello.js<br><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></pre></td><td class="code"><pre><span class="line"><span class="keyword">const</span> hello = {</span><br><span class="line"> say: <span class="function"><span class="params">arg</span> =></span> {</span><br><span class="line"> <span class="built_in">console</span>.info(<span class="string">'hello '</span> + arg || <span class="string">'world'</span>);</span><br><span class="line"> }</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line"><span class="keyword">export</span> <span class="keyword">default</span> hello;</span><br></pre></td></tr></table></figure></p>
<p>index.js<br><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></pre></td><td class="code"><pre><span class="line"><span class="keyword">import</span> Hello <span class="keyword">from</span> <span class="string">'./hello'</span>;</span><br><span class="line"></span><br><span class="line">Hello.say(<span class="string">'man'</span>);</span><br></pre></td></tr></table></figure></p>
<p><code>index.js</code> 作为入口文件，引用了 <code>hello.js</code> 模块。</p>
<h1 id="Webpack-打包"><a href="#Webpack-打包" class="headerlink" title="Webpack 打包"></a>Webpack 打包</h1><p>在命令行执行 <code>webpack index.js bundle.js</code> 对入口文件进行打包，生成 <code>bundle.js</code> ，大体结构为（为了方便阅读，我删除了部分多余的代码）：<br><img src="http://7xiyp1.com1.z0.glb.clouddn.com/2018-05-23-17-33-27-2018523173328.png" alt="2018-05-23-17-33-27-2018523173328"></p>
<p>可以看到，最终生成的文件以 <code>(function (modules) {})([模块1, 模块2])</code> 的方式启动，我们定义的模块被包装成一个个匿名函数，然后以数组的形式传递个一个匿名函数 <code>function (modules) {}</code>，在这个匿名函数中定义了一个 <code>__webpack_require__()</code> 函数，用来加载模块，最后，通过 <code>return __webpack_require__(__webpack_require__.s = 0);</code> 来加载第一个模块 <code>index.js</code></p>
<h1 id="webpack-require-函数"><a href="#webpack-require-函数" class="headerlink" title="webpack_require() 函数"></a><strong>webpack_require</strong>() 函数</h1><p>该函数接收一个 <code>moduleId</code> 作为参数，这个参数就是各个模块在数组中的索引，<br><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><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br><span class="line">32</span><br><span class="line">33</span><br><span class="line">34</span><br></pre></td><td class="code"><pre><span class="line"><span class="function"><span class="keyword">function</span> <span class="title">__webpack_require__</span>(<span class="params">moduleId</span>) </span>{</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="comment">/******/</span> <span class="comment">// Check if module is in cache</span></span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="keyword">if</span> (installedModules[moduleId]) {</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="keyword">return</span> installedModules[moduleId].exports;</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> }</span><br><span class="line"> <span class="comment">/******/</span> <span class="comment">// Create a new module (and put it into the cache)</span></span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="keyword">var</span> <span class="built_in">module</span> = installedModules[moduleId] = {</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> i: moduleId,</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> l: <span class="literal">false</span>,</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> exports: {}</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> };</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="comment">/******/</span> <span class="comment">// Execute the module function</span></span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> modules[moduleId].call(<span class="built_in">module</span>.exports, <span class="built_in">module</span>, <span class="built_in">module</span>.exports, __webpack_require__);</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="comment">/******/</span> <span class="comment">// Flag the module as loaded</span></span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="built_in">module</span>.l = <span class="literal">true</span>;</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="comment">/******/</span> <span class="comment">// Return the exports of the module</span></span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> <span class="keyword">return</span> <span class="built_in">module</span>.exports;</span><br><span class="line"> <span class="comment">/******/</span></span><br><span class="line"> }</span><br></pre></td></tr></table></figure></p>
<p>其中 <code>installedModules</code> 是用来缓存执行过的模块。通过 <code>modules[moduleId].call()</code> 来执行模块，最后返回模块的 exports。</p>
<h1 id="模块接受的参数"><a href="#模块接受的参数" class="headerlink" title="模块接受的参数"></a>模块接受的参数</h1><p>以 <code>hello.js</code> 模块为例<br><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></pre></td><td class="code"><pre><span class="line">(<span class="function"><span class="keyword">function</span> (<span class="params">module, __webpack_exports__, __webpack_require__</span>) </span>{</span><br><span class="line"></span><br><span class="line"><span class="meta"> "use strict"</span>;</span><br><span class="line"> <span class="keyword">const</span> hello = {</span><br><span class="line"> say: <span class="function"><span class="params">arg</span> =></span> {</span><br><span class="line"> <span class="built_in">console</span>.info(<span class="string">'hello '</span> + arg || <span class="string">'world'</span>);</span><br><span class="line"> }</span><br><span class="line"> };</span><br><span class="line"></span><br><span class="line"> <span class="comment">/* harmony default export */</span></span><br><span class="line"> __webpack_exports__[<span class="string">"a"</span>] = (hello);</span><br><span class="line"></span><br><span class="line"> <span class="comment">/***/</span></span><br><span class="line">})</span><br></pre></td></tr></table></figure></p>
<p>webpack 会向模块传递 <code>module, __webpack_exports__, __webpack_require__</code> 三个参数，前两个是用来导出模块内的变量，第三个参数为前面介绍的 <code>__webpack_require__()</code> 的引用，用来导入其它模块。</p>
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函数节流（throttle）与函数去抖（debounce）的区别
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<p>以前在做一些性能小优化的时候会用到 “debounce” 这种技巧，特别是在处理一些 DOM 事件上。今天了解到原来还有一个跟它类似的叫 “throttle” 的玩意，一开始看上去感觉没多大的差别，仔细阅读代码，发现它们无论是在代码逻辑和应用场景上都是有很大的区别的。</p>
<h2 id="函数节流（throttle）是什么"><a href="#函数节流（throttle）是什么" class="headerlink" title="函数节流（throttle）是什么"></a>函数节流（throttle）是什么</h2><blockquote>
<p>函数节流（throttle）用来限制单位时间的函数被调用的最大次数</p>
</blockquote>
<p>比方说下面这段代码中的 <code>fn()</code> 每 <code>100ms</code> 只能执行一次，那么 <code>1s</code> 内它最多只能执行10次：<br><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></pre></td><td class="code"><pre><span class="line"><span class="keyword">var</span> throttle = <span class="function"><span class="keyword">function</span>(<span class="params">action, delay</span>)</span>{</span><br><span class="line"> <span class="keyword">var</span> last = <span class="number">0</span>;</span><br><span class="line"> <span class="keyword">return</span> <span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>{</span><br><span class="line"> <span class="keyword">var</span> curr = +<span class="keyword">new</span> <span class="built_in">Date</span>();</span><br><span class="line"> <span class="keyword">if</span> (curr - last > delay)</span><br><span class="line"> action.apply(<span class="keyword">this</span>, <span class="built_in">arguments</span>);</span><br><span class="line"> last = curr;</span><br><span class="line"> };</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line">func () {</span><br><span class="line"> <span class="comment">// ...</span></span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> fn = throttle(func, <span class="number">100</span>);</span><br></pre></td></tr></table></figure></p>
<h2 id="函数去抖（debounce）是什么"><a href="#函数去抖（debounce）是什么" class="headerlink" title="函数去抖（debounce）是什么"></a>函数去抖（debounce）是什么</h2><blockquote>
<p>函数去抖（debounce）规定了函数在指定的时间内不能被再次调用，如果在这期间被调用了，那么执行等待时间将会被刷新</p>
</blockquote>
<p>比方说下面这段代码中的 <code>fn()</code> 被调用后，要等待 <code>100ms</code> 函数 <code>func</code> 才会被执行，如果在这期间， <code>fn()</code> 又被调用了，那么等待时间将从调用的那一刻重新算起。<br><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> debounce = <span class="function"><span class="keyword">function</span>(<span class="params">action, idle</span>)</span>{</span><br><span class="line"> <span class="keyword">var</span> last;</span><br><span class="line"> <span class="keyword">return</span> <span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>{</span><br><span class="line"> <span class="keyword">var</span> ctx = <span class="keyword">this</span>, args = <span class="built_in">arguments</span>;</span><br><span class="line"> clearTimeout(last);</span><br><span class="line"> last = setTimeout(<span class="function"><span class="keyword">function</span>(<span class="params"></span>)</span>{</span><br><span class="line"> action.apply(ctx, args);</span><br><span class="line"> }, idle);</span><br><span class="line"> };</span><br><span class="line">};</span><br><span class="line"></span><br><span class="line">func () {</span><br><span class="line"> <span class="comment">// ...</span></span><br><span class="line">}</span><br><span class="line"></span><br><span class="line"><span class="keyword">var</span> fn = debounce(func, <span class="number">100</span>);</span><br></pre></td></tr></table></figure></p>
<h2 id="Demo"><a href="#Demo" class="headerlink" title="Demo"></a>Demo</h2><p>借用一个第三方示例：<br>
<iframe height="265" scrolling="no" src="//codepen.io/chriscoyier/embed/vOZNQV/?height=265&theme-id=0&default-tab=js,result&embed-version=2" frameborder="no" allowtransparency="true" allowfullscreen="true" style="width: 100%;">See the Pen <a href="http://codepen.io/chriscoyier/pen/vOZNQV/" target="_blank" rel="noopener">The Difference Between Throttling, Debouncing, and Neither</a> by Chris Coyier (<a href="http://codepen.io/chriscoyier" target="_blank" rel="noopener">@chriscoyier</a>) on <a href="http://codepen.io" target="_blank" rel="noopener">CodePen</a>.
</iframe>
</p>
<hr>
<p>参考资料：</p>
<ul>
<li><a href="https://css-tricks.com/the-difference-between-throttling-and-debouncing/" target="_blank" rel="noopener">https://css-tricks.com/the-difference-between-throttling-and-debouncing/</a></li>
</ul>
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