Socket.IO学习之基础入门

这里贴出Socket.IO官网

一.Socket.IO的介绍

Socket.IO支持及时、双向与基于事件的交流。它可以在每个平台、每个浏览器和每个设备上工作，可靠性和速度同样稳定。

• 实时分析：将数据推送到客户端，这些客户端会被表示为实时计数器，图表或日志客户。
• 实时通信和聊天：只需几行代码便可写成一个Socket.IO的”Hello,World”聊天应用。
• 二进制流传输：从1.0版本开始，Socket.IO支持任何形式的二进制文件传输，例如：图片，视频，音频等。
• 文档合并：允许多个用户同时编辑一个文档，并且能够看到每个用户做出的修改。

官方上提供了三个demo：多人聊天室、多人玩游戏、远程控制电脑。大家可以去官网试一试。

二.写一个聊天应用

在这个教程中，我们将创建一个基本的聊天应用，它基本不需要你拥有一点的Node.js或者Socket.IO的知识，所以它适合所有级别的开发者。

1.介绍：

使用流行的web应用程序栈，例如LAMP (PHP)，写一个聊天应用是非常困难的。它会涉及到轮询服务器的更改，跟踪时间戳，并且它运行的比较慢。

套接字通常支撑着大多数实时聊天系统的架构，提供了在服务器和客户端之间双向通信的通道。

这意味着服务器可以向客户端推送消息，无论你何时写一个聊天消息，主意就是服务器将会得到这个消息，并将这个消息推送给连接到服务器的其他客户端。

2.web框架

第一步是搭建一个简单的HTML网页，该网页提供了一个表单和一系列消息。我们将使用Node.js的web框架Express，确保Node.js已经被安装了。

首先创建一个package.json文件，来描述我们的工程，我建议你把它放在一个空的目录中(我叫它chat-example)，

<code class="hljs json has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;">{  "<span class="hljs-attribute" style="box-sizing: border-box;">name</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"socket-chat-example"</span></span>,  "<span class="hljs-attribute" style="box-sizing: border-box;">version</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1.0.0"</span></span>,  "<span class="hljs-attribute" style="box-sizing: border-box;">description</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"my first socket.io app"</span></span>,  "<span class="hljs-attribute" style="box-sizing: border-box;">main</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"index.js"</span></span>,  "<span class="hljs-attribute" style="box-sizing: border-box;">scripts</span>": <span class="hljs-value" style="box-sizing: border-box;">{    "<span class="hljs-attribute" style="box-sizing: border-box;">test</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"start index.js"</span>  </span>}</span>,  "<span class="hljs-attribute" style="box-sizing: border-box;">author</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">""</span></span>,  "<span class="hljs-attribute" style="box-sizing: border-box;">license</span>": <span class="hljs-value" style="box-sizing: border-box;"><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ISC"</span></span>}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

现在，为了将我们需要的东西安装在依赖项中，我们使用这个命令：

<code class="hljs brainfuck has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">npm</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">install</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">-</span><span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">-</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">save</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

现在，我们安装一下Express：

<code class="hljs brainfuck has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">$</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">npm</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">install</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">-</span><span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">-</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">save</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">express</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

既然express已经被安装好了，我们可以创建一个index.js文件来来设置应用。

<code class="hljs javascript has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> app = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">require</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'express'</span>)();<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> http = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">require</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'http'</span>).Server(app);app.get(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'/'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(req, res)</span>{</span>  res.send(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'<h1>Hello world</h1>'</span>);});http.listen(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3000</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span>{</span>  console.log(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'listening on *:3000'</span>);});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li></ul>

这将会做三件事件：

• Express将app初始化成一个函数处理器，你可以将其提供给一个HTTP服务器(看第二行)
• 我们定义一个路由处理器，当我们访问网站主页时，这个处理器就会被调用。
• 我们让这个http服务器监听3000端口。

如果你运行node index.js，你会看到下面的图示：

3.提供HTML

到目前为止，在index.js文件中，我们调用了res.send()这个方法，并将HTML类型的字符串传递给它。如果把整个应用的HTML放在那儿的话，我们的代码看起来会非常奇怪。相反，我们将会创建一个index.html文件，并提供它。

我们使用sendFile()方法来重构路由处理器：

<code class="hljs actionscript has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;">app.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">get</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'/'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(req, res)</span>{</span>  res.sendFile(__dirname + <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'/index.html'</span>);});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

使用以下的代码来填写index.html文件：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-doctype" style="color: rgb(102, 0, 102); box-sizing: border-box;"><!doctype html></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">html</span>></span>  <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">head</span>></span>    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">title</span>></span>Socket.IO chat<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">title</span>></span>    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">style</span>></span><span class="css" style="box-sizing: border-box;">      * <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">box-sizing</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> border-box</span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">body</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">font</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">13</span>px Helvetica, Arial</span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">form</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#000</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">3</span>px</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">position</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> fixed</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">bottom</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">width</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">100</span>%</span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">form</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">input</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">10</span>px</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">width</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">90</span>%</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin-right</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> .<span class="hljs-number" style="box-sizing: border-box;">5</span>%</span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">form</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">button</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">width</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">9</span>%</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-function" style="box-sizing: border-box;">rgb(<span class="hljs-number" style="box-sizing: border-box;">130</span>, <span class="hljs-number" style="box-sizing: border-box;">224</span>, <span class="hljs-number" style="box-sizing: border-box;">255</span>)</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">border</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> none</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">10</span>px</span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-id" style="box-sizing: border-box; color: rgb(155, 112, 63);">#messages</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">list-style-type</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> none</span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">margin</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">0</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-id" style="box-sizing: border-box; color: rgb(155, 112, 63);">#messages</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">li</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">padding</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-number" style="box-sizing: border-box;">5</span>px <span class="hljs-number" style="box-sizing: border-box;">10</span>px</span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>      <span class="hljs-id" style="box-sizing: border-box; color: rgb(155, 112, 63);">#messages</span> <span class="hljs-tag" style="color: rgb(0, 0, 0); box-sizing: border-box;">li</span><span class="hljs-pseudo" style="color: rgb(0, 0, 0); box-sizing: border-box;">:nth-child(odd)</span> <span class="hljs-rules" style="box-sizing: border-box;">{ <span class="hljs-rule" style="box-sizing: border-box;"><span class="hljs-attribute" style="box-sizing: border-box;">background</span>:<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 102, 102);"> <span class="hljs-hexcolor" style="box-sizing: border-box;">#eee</span></span></span>; <span class="hljs-rule" style="box-sizing: border-box;">}</span></span>    </span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">style</span>></span>  <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">head</span>></span>  <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">body</span>></span>    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">ul</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"messages"</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">ul</span>></span>    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">form</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">action</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">""</span>></span>      <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">input</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">id</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"m"</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">autocomplete</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"off"</span> /></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">button</span>></span>Send<span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">button</span>></span>    <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">form</span>></span>  <span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">body</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">html</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li></ul>

如果你重启这个进程，然后重新刷新页面，看起来是这样的：

4.集成Socket.IO

Socket.IO由两部分构成：

• socket.io：一个服务器，集成了Node.JS的HTTP服务器
• socket.io-client：一个客户端库，在浏览器端加载

在开发期间，socket.io会自动为我们提供客户端，所以现在我们只需安装一个模块：

<code class="hljs brainfuck has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">npm</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">install</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">-</span><span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">-</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">save</span> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">socket</span><span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">.</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">io</span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

这个命令会安装socket.io模块，并将依赖项添加到package.json文件中，现在我们在index.js添加一些代码：

<code class="hljs javascript has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> app = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">require</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'express'</span>)();<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> http = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">require</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'http'</span>).Server(app);<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> io = <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">require</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'socket.io'</span>)(http);app.get(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'/'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(req, res)</span>{</span>  res.sendfile(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'index.html'</span>);});io.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'connection'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(socket)</span>{</span>  console.log(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'a user connected'</span>);});http.listen(<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">3000</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span>{</span>  console.log(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'listening on *:3000'</span>);});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li></ul>

注意到，我传递了一个http(HTTP Server)对象来创建一个新的socket.io实例，然后，为即将来到的套接字监听connection事件，我会将其打印到控制台中。

现在，我在index.html文件中，在</body>之前添加了以下的代码段：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">script</span> <span class="hljs-attribute" style="box-sizing: border-box; color: rgb(102, 0, 102);">src</span>=<span class="hljs-value" style="box-sizing: border-box; color: rgb(0, 136, 0);">"/socket.io/socket.io.js"</span>></span><span class="javascript" style="box-sizing: border-box;"></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">script</span>></span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">script</span>></span><span class="javascript" style="box-sizing: border-box;">  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> socket = io();</span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">script</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li></ul>

上面的代码段会加载socket.io-client，它暴露了io这个全局变量，然后进行连接。

注意到，我在调用io()的时候，并没有声明任何URL，因为它默认是尝试连接提供网页的主机。

如果你现在重新加载服务器和网页，你会发现控制台会打印“a user connected”。尽力打开几个标签，你会发现控制台会打印出多个消息。

每个socket也会发射特殊的disconnect事件：

<code class="hljs matlab has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-transposed_variable" style="box-sizing: border-box;">io.</span>on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'connection'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(socket)</span>{</span>  <span class="hljs-transposed_variable" style="box-sizing: border-box;">console.</span><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">log</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'a user connected'</span>);  <span class="hljs-transposed_variable" style="box-sizing: border-box;">socket.</span>on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'disconnect'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span>{</span>    <span class="hljs-transposed_variable" style="box-sizing: border-box;">console.</span><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">log</span>(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'user disconnected'</span>);  });});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li></ul>

如果你多次刷新一个标签的话，你会马上看到：

5.发射事件

Socket.IO背后的思想是你可以发射和接收你想要的任何事件，携带你想要的任何数据。任何能够被转换成JSON的对象都能这样做，包括二进制数据。

让我们实现一个效果，当用户输入一条消息时，服务器会把它当作是一个chat message事件，index.html中script(脚本)部分应当是这样了：

在index.js中，我们打印出chat message事件：

<code class="hljs lua has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">io</span>.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'connection'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(socket)</span></span>{  socket.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'chat message'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(msg)</span></span>{    console.log(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'message: '</span> + msg);  });});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

6.广播

接下来我们打算使用服务器来向其他的客户端发射事件，为了能够向每个人都发射事件，Socket.IO为我们提供了io.emit()方法：

<code class="hljs lua has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">io</span>.emit(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'some event'</span>, { <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">for</span>: <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'everyone'</span> });</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li></ul>

如果你想要发送消息给每个人，除了某个特定的套接字，我们有broadcast标识：

<code class="hljs lua has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">io</span>.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'connection'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(socket)</span></span>{  socket.broadcast.emit(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'hi'</span>);});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li></ul>

这个例子中，为了简洁性，我们将把消息发送给任何人，包括发送的客户端：

<code class="hljs lua has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">io</span>.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'connection'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(socket)</span></span>{  socket.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'chat message'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(msg)</span></span>{    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">io</span>.emit(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'chat message'</span>, msg);  });});</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li></ul>

在客户端，当捕获到chat message事件的时候，我们会将它展示在页面上，整个客户端的JavaScript代码如下面所示：

<code class="hljs xml has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"><<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">script</span>></span><span class="javascript" style="box-sizing: border-box;">  <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">var</span> socket = io();  $(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'form'</span>).submit(<span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">()</span>{</span>    socket.emit(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'chat message'</span>, $(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'#m'</span>).val());    $(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'#m'</span>).val(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">''</span>);    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> <span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">false</span>;  });  socket.on(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'chat message'</span>, <span class="hljs-function" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">function</span><span class="hljs-params" style="color: rgb(102, 0, 102); box-sizing: border-box;">(msg)</span>{</span>    $(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'#messages'</span>).append($(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">'<li>'</span>).text(msg));  });</span><span class="hljs-tag" style="color: rgb(0, 102, 102); box-sizing: border-box;"></<span class="hljs-title" style="box-sizing: border-box; color: rgb(0, 0, 136);">script</span>></span></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right: 1px solid rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li></ul>

至此，我们的聊天应用已经完成了，大约20多行代码。

你可以在这里获得源代码。

<code class="hljs ruby has-numbering" style="display: block; padding: 0px; background: transparent; color: inherit; box-sizing: border-box; font-family: "Source Code Pro", monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal;"><span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">$ </span>git clone <span class="hljs-symbol" style="color: rgb(0, 102, 102); box-sizing: border-box;">https:</span>/<span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/github.com/guille</span><span class="hljs-regexp" style="color: rgb(0, 136, 0); box-sizing: border-box;">/chat-example.git</span></code>