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<!DOCTYPE html>
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RxJs学习笔记(一) |
Zhangdi'Blog --- 爱技术爱折腾,无折腾不技术.
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<ol class="post-toc"><li class="post-toc-item post-toc-level-4"><a class="post-toc-link" href="#RxJs是什么？"><span class="post-toc-text">RxJs是什么？</span></a><ol class="post-toc-child"><li class="post-toc-item post-toc-level-5"><a class="post-toc-link" href="#1-新建工程"><span class="post-toc-text">1. 新建工程</span></a></li><li class="post-toc-item post-toc-level-5"><a class="post-toc-link" href="#2-配置webpack"><span class="post-toc-text">2. 配置webpack</span></a></li><li class="post-toc-item post-toc-level-5"><a class="post-toc-link" href="#3-实践RxJs-在public-下新建-index-html"><span class="post-toc-text">3. 实践RxJs 在public 下新建 index.html</span></a></li></ol></li></ol></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#纯净性-Purity"><span class="post-toc-text">纯净性 (Purity)</span></a></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#流动性-Flow"><span class="post-toc-text">流动性 (Flow)</span></a></li><li class="post-toc-item post-toc-level-3"><a class="post-toc-link" href="#值-Values"><span class="post-toc-text">值 (Values)</span></a>
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RxJs学习笔记(一)
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<span>2月 08, 2018</span>
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<h4 id="RxJs是什么？"><a href="#RxJs是什么？" class="headerlink" title="RxJs是什么？"></a>RxJs是什么？</h4><blockquote>
<p><code>RxJS</code> 是一个库，它通过使用 <code>observable</code> 序列来编写异步和基于事件的程序。它提供了一个核心类型 <code>Observable</code>，附属类型 (<code>Observer</code>、 <code>Schedulers</code>、 <code>Subjects</code>) 和受 [Array#extras] 启发的操作符 (<code>map</code>、<code>filter</code>、<code>reduce</code>、<code>every</code>, 等等)，这些数组操作符可以把异步事件作为集合来处理。</p>
</blockquote>
<p><code>ReactiveX</code> 结合了 观察者模式、迭代器模式 和 使用集合的函数式编程，以满足以一种理想方式来管理事件序列所需要的一切。</p>
<p>RxJS 中用来解决异步事件管理的的基本概念：</p>
<ul>
<li><code>Observable</code> (可观察对象): 表示一个概念，这个概念是一个可调用的未来值或事件的集合。</li>
<li><code>Observer</code> (观察者): 一个回调函数的集合，它知道如何去监听由 <code>Observable</code> 提供的值。</li>
<li><code>Subscription</code> (订阅): 表示 <code>Observable</code> 的执行，主要用于取消 <code>Observable</code> 的执行。</li>
<li><code>Operators</code> (操作符): 采用函数式编程风格的纯函数 (pure function)，使用像 <code>map</code>、<code>filter</code>、<code>concat</code>、<code>flatMap</code> 等这样的操作符来处理集合。</li>
<li><code>Subject</code> (主体): 相当于 <code>EventEmitter</code>，并且是将值或事件多路推送给多个 <code>Observer</code> 的唯一方式。</li>
<li><code>Schedulers</code> (调度器): 用来控制并发并且是中央集权的调度员，允许我们在发生计算时进行协调，例如 <code>setTimeout</code> 或 <code>requestAnimationFrame</code> 或其他。</li>
</ul>
<p>示例：</p>
<p>注册事件监听器的常规写法。</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">var</span> button <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'button'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
button<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'Clicked!'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>使用 RxJS 的话，创建一个 observable 来代替。</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">var</span> button <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">querySelector</span><span class="token punctuation">(</span><span class="token string">'button'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
Rx<span class="token punctuation">.</span>Observable<span class="token punctuation">.</span><span class="token function">fromEvent</span><span class="token punctuation">(</span>button<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token string">'Clicked!'</span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>以上是对RxJs的基本示例，下面搭建一个 webpack + babel 的工程来做一些简单的演示。（顺便复习webpack配置）</p>
<h5 id="1-新建工程"><a href="#1-新建工程" class="headerlink" title="1. 新建工程"></a>1. 新建工程</h5><pre class=" language-bash"><code class="language-bash"><span class="token function">mkdir</span> rxjs-demo <span class="token operator">&&</span> <span class="token function">cd</span> rxjs-demo
yarn init
yarn add webpack webpack-dev-server babel babel-loader babel-preset-env rxjs
<span class="token function">mkdir</span> src
<span class="token function">mkdir</span> public
</code></pre>
<p> 因为使用 ES6语法，所以使用 babel-loader babel-preset-env;</p>
<h5 id="2-配置webpack"><a href="#2-配置webpack" class="headerlink" title="2. 配置webpack"></a>2. 配置webpack</h5><p>新建 <code>webpack.config.js</code> </p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">const</span> path <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'path'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> webpack <span class="token operator">=</span> <span class="token function">require</span><span class="token punctuation">(</span><span class="token string">'webpack'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
module<span class="token punctuation">.</span>exports <span class="token operator">=</span> <span class="token punctuation">{</span>
entry<span class="token punctuation">:</span>path<span class="token punctuation">.</span><span class="token function">join</span><span class="token punctuation">(</span>__dirname<span class="token punctuation">,</span><span class="token string">'src/index.js'</span><span class="token punctuation">)</span><span class="token punctuation">,</span><span class="token comment" spellcheck="true">//配置入口</span>
output<span class="token punctuation">:</span><span class="token punctuation">{</span>
path<span class="token punctuation">:</span>path<span class="token punctuation">.</span><span class="token function">resolve</span><span class="token punctuation">(</span><span class="token string">'dist'</span><span class="token punctuation">)</span><span class="token punctuation">,</span>
filename<span class="token punctuation">:</span><span class="token string">'bundle.js'</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
devServer<span class="token punctuation">:</span><span class="token punctuation">{</span>
contentBase<span class="token punctuation">:</span> <span class="token string">"./public"</span><span class="token punctuation">,</span> <span class="token comment" spellcheck="true">//本地服务器所加载的页面所在的目录</span>
historyApiFallback<span class="token punctuation">:</span> <span class="token boolean">true</span><span class="token punctuation">,</span> <span class="token comment" spellcheck="true">//不跳转</span>
inline<span class="token punctuation">:</span> <span class="token boolean">true</span><span class="token punctuation">,</span>
hot<span class="token punctuation">:</span> <span class="token boolean">true</span> <span class="token comment" spellcheck="true">//热更新</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
module<span class="token punctuation">:</span><span class="token punctuation">{</span>
rules<span class="token punctuation">:</span><span class="token punctuation">[</span>
<span class="token punctuation">{</span>
test<span class="token punctuation">:</span><span class="token regex">/\.js$/</span><span class="token punctuation">,</span>
use<span class="token punctuation">:</span><span class="token punctuation">{</span>
loader<span class="token punctuation">:</span><span class="token string">'babel-loader'</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
exclude<span class="token punctuation">:</span><span class="token operator">/</span>node_module<span class="token operator">/</span> <span class="token comment" spellcheck="true">//排除node_module</span>
<span class="token punctuation">}</span>
<span class="token punctuation">]</span>
<span class="token punctuation">}</span><span class="token punctuation">,</span>
plugins<span class="token punctuation">:</span><span class="token punctuation">[</span>
<span class="token keyword">new</span> <span class="token class-name">wenpack<span class="token punctuation">.</span>HotModuleReplacementPlugin</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token comment" spellcheck="true">//添加热更新插件</span>
<span class="token punctuation">]</span>
<span class="token punctuation">}</span>
</code></pre>
<p>修改package.json </p>
<pre class=" language-json"><code class="language-json">//添加
<span class="token property">"scripts"</span><span class="token operator">:</span><span class="token punctuation">{</span>
<span class="token property">"start"</span><span class="token operator">:</span><span class="token string">"webpack-dev-server --open"</span>
<span class="token punctuation">}</span>
</code></pre>
<p>Ok，webpack配置完成。</p>
<h5 id="3-实践RxJs-在public-下新建-index-html"><a href="#3-实践RxJs-在public-下新建-index-html" class="headerlink" title="3. 实践RxJs 在public 下新建 index.html"></a>3. 实践RxJs 在public 下新建 <code>index.html</code></h5><pre class=" language-html"><code class="language-html"><span class="token doctype"><!doctype html></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>html</span> <span class="token attr-name">lang</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>zh-cn<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>head</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>meta</span> <span class="token attr-name">charset</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>UTF-8<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>meta</span> <span class="token attr-name">name</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>viewport<span class="token punctuation">"</span></span> <span class="token attr-name">content</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>width<span class="token punctuation">=</span>device-width, user-scalable<span class="token punctuation">=</span>no, initial-scale<span class="token punctuation">=</span>1.0, maximum-scale<span class="token punctuation">=</span>1.0, minimum-scale<span class="token punctuation">=</span>1.0<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>meta</span> <span class="token attr-name">http-equiv</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>X-UA-Compatible<span class="token punctuation">"</span></span> <span class="token attr-name">content</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>ie<span class="token punctuation">=</span>edge<span class="token punctuation">"</span></span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>title</span><span class="token punctuation">></span></span>RxJs<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>title</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>head</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>body</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>div</span> <span class="token attr-name">id</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>root<span class="token punctuation">"</span></span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>div</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"><</span>script</span> <span class="token attr-name">src</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>bundle.js<span class="token punctuation">"</span></span><span class="token punctuation">></span></span><span class="token tag"><span class="token tag"><span class="token punctuation"></</span>script</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>body</span><span class="token punctuation">></span></span>
<span class="token tag"><span class="token tag"><span class="token punctuation"></</span>html</span><span class="token punctuation">></span></span>
</code></pre>
<p>在src下新建<code>index.js</code> </p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">import</span> Rx <span class="token keyword">from</span> <span class="token string">'rxjs/Rx'</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> root <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">getElementById</span><span class="token punctuation">(</span><span class="token string">'root'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> createButton <span class="token operator">=</span> <span class="token punctuation">(</span>buttonName<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
<span class="token keyword">let</span> button <span class="token operator">=</span> document<span class="token punctuation">.</span><span class="token function">createElement</span><span class="token punctuation">(</span><span class="token string">'button'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
button<span class="token punctuation">.</span>innerHTML <span class="token operator">=</span> buttonName<span class="token punctuation">;</span>
root<span class="token punctuation">.</span><span class="token function">appendChild</span><span class="token punctuation">(</span>button<span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">return</span> button<span class="token punctuation">;</span>
<span class="token punctuation">}</span><span class="token punctuation">;</span>
</code></pre>
<p>执行 <code>yarn start</code></p>
<hr>
<h3 id="纯净性-Purity"><a href="#纯净性-Purity" class="headerlink" title="纯净性 (Purity)"></a>纯净性 (Purity)</h3><p>使得 RxJS 强大的正是它使用纯函数来产生值的能力。这意味着你的代码更不容易出错。</p>
<p>通常你会创建一个非纯函数，这个函数之外也使用了共享变量的代码会把将你的应用状态搞得一团糟。</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">let</span> globalCount <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> btn1 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'RxJs方式'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> btn2 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'常规方式'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token keyword">const</span> btn3 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'检查GlobalCount'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token comment" spellcheck="true">// scan 操作符的工作原理与数组的 reduce 类似。</span>
<span class="token comment" spellcheck="true">// 它需要一个暴露给回调函数当参数的初始值。每次回调函数运行后的返回值会作为下次回调函数运行时的参数。</span>
Rx<span class="token punctuation">.</span>Observable<span class="token punctuation">.</span><span class="token function">fromEvent</span><span class="token punctuation">(</span>btn1<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">scan</span><span class="token punctuation">(</span>count <span class="token operator">=</span><span class="token operator">></span> count <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span> count <span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>count<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
btn2<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token template-string"><span class="token string">`当前globalCount:</span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span><span class="token operator">++</span>globalCount<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string">`</span></span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
Rx<span class="token punctuation">.</span>Observable<span class="token punctuation">.</span><span class="token function">fromEvent</span><span class="token punctuation">(</span>btn3<span class="token punctuation">,</span><span class="token string">'click'</span><span class="token punctuation">)</span><span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token function">alert</span><span class="token punctuation">(</span>globalCount<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<h3 id="流动性-Flow"><a href="#流动性-Flow" class="headerlink" title="流动性 (Flow)"></a>流动性 (Flow)</h3><p>RxJS 提供了一整套操作符来帮助你控制事件如何流经 observables 。</p>
<p>下面的代码展示的是如何控制一秒钟内最多点击一次，先来看使用普通的 JavaScript：</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">let</span> count <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">let</span> rate <span class="token operator">=</span> <span class="token number">1000</span><span class="token punctuation">;</span>
<span class="token keyword">let</span> lastClick <span class="token operator">=</span> Date<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> rate<span class="token punctuation">;</span>
<span class="token keyword">const</span> btn4 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'每秒最多点击一次-原生'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
btn4<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>Date<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> lastClick <span class="token operator">>=</span> rate<span class="token punctuation">)</span> <span class="token punctuation">{</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token template-string"><span class="token string">`Clicked </span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span><span class="token operator">++</span>count<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string"> times`</span></span><span class="token punctuation">)</span><span class="token punctuation">;</span>
lastClick <span class="token operator">=</span> Date<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>使用 RxJS：</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">const</span> btn5 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'每秒最多点击一次-RxJs'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
Rx<span class="token punctuation">.</span>Observable<span class="token punctuation">.</span><span class="token function">fromEvent</span><span class="token punctuation">(</span>btn5<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">throttleTime</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">scan</span><span class="token punctuation">(</span>count <span class="token operator">=</span><span class="token operator">></span> count <span class="token operator">+</span> <span class="token number">1</span><span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span>count <span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span><span class="token template-string"><span class="token string">`Clicked </span><span class="token interpolation"><span class="token interpolation-punctuation punctuation">${</span>count<span class="token interpolation-punctuation punctuation">}</span></span><span class="token string"> times`</span></span><span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>其他流程控制操作符有 filter 、delay、debounceTime、take、takeUntil、distinct、distinctUntilChanged 等。</p>
<h3 id="值-Values"><a href="#值-Values" class="headerlink" title="值 (Values)"></a>值 (Values)</h3><p>对于流经 observables 的值，你可以对其进行转换。</p>
<p>下面的代码展示的是如何累加每次点击的鼠标 x 坐标，先来看使用普通的 JavaScript：</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">let</span> count <span class="token operator">=</span> <span class="token number">0</span><span class="token punctuation">;</span>
<span class="token keyword">let</span> rate <span class="token operator">=</span> <span class="token number">1000</span><span class="token punctuation">;</span>
<span class="token keyword">let</span> lastClick <span class="token operator">=</span> Date<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> rate<span class="token punctuation">;</span>
<span class="token keyword">const</span> btn6 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'原生'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
btn6<span class="token punctuation">.</span><span class="token function">addEventListener</span><span class="token punctuation">(</span><span class="token string">'click'</span><span class="token punctuation">,</span> <span class="token punctuation">(</span>event<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> <span class="token punctuation">{</span>
<span class="token keyword">if</span> <span class="token punctuation">(</span>Date<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token operator">-</span> lastClick <span class="token operator">>=</span> rate<span class="token punctuation">)</span> <span class="token punctuation">{</span>
count <span class="token operator">+</span><span class="token operator">=</span> event<span class="token punctuation">.</span>clientX<span class="token punctuation">;</span>
console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>count<span class="token punctuation">)</span>
lastClick <span class="token operator">=</span> Date<span class="token punctuation">.</span><span class="token function">now</span><span class="token punctuation">(</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
<span class="token punctuation">}</span>
<span class="token punctuation">}</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>使用 RxJS：</p>
<pre class=" language-javascript"><code class="language-javascript"><span class="token keyword">const</span> btn7 <span class="token operator">=</span> <span class="token function">createButton</span><span class="token punctuation">(</span><span class="token string">'RxJs'</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
Rx<span class="token punctuation">.</span>Observable<span class="token punctuation">.</span><span class="token function">fromEvent</span><span class="token punctuation">(</span>btn7<span class="token punctuation">,</span> <span class="token string">'click'</span><span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">throttleTime</span><span class="token punctuation">(</span><span class="token number">1000</span><span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">map</span><span class="token punctuation">(</span>event <span class="token operator">=</span><span class="token operator">></span> event<span class="token punctuation">.</span>clientX<span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">scan</span><span class="token punctuation">(</span><span class="token punctuation">(</span>count<span class="token punctuation">,</span> clientX<span class="token punctuation">)</span> <span class="token operator">=</span><span class="token operator">></span> count <span class="token operator">+</span> clientX<span class="token punctuation">,</span> <span class="token number">0</span><span class="token punctuation">)</span>
<span class="token punctuation">.</span><span class="token function">subscribe</span><span class="token punctuation">(</span>count <span class="token operator">=</span><span class="token operator">></span> console<span class="token punctuation">.</span><span class="token function">log</span><span class="token punctuation">(</span>count<span class="token punctuation">)</span><span class="token punctuation">)</span><span class="token punctuation">;</span>
</code></pre>
<p>其他产生值的操作符有pluck、pairwise、sample等。</p>
<p>未完待续…</p>
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