Socket.IO 客户端 API IO

IO

创建方式

<script src="/socket.io/socket.io.js"></script>
<script>
  const socket = io('http://localhost');
</script>

或者使用require或import

const io = require('socket.io-client');
// or with import syntax
import io from 'socket.io-client';

io.protocol

• Nubmer

协议修订号

io([url][, options])

• url 默认为window.location
• options (Object) forceNew是否重用已存在的连接
• return Socket

为给定的URL创建一个Manager，并且在后续的调用中重用该连接，除非设置forceNew:true或'force new connection': true

查询参数可以在query中提供，也可以在URL中提供

---

初始化例子

多路复用

默认情况下，连接到不同的命名空间使用单个连接，可以通过设置options的forceNew来禁用

const socket = io();
const adminSocket = io('/admin');
// a single connection will be established

const adminSocket = io('/admin', { forceNew: true });
// will create two distinct connections

const socket = io();
const socket2 = io();
// will also create two distinct connections

注意：重用相同的命名空间，将创建两个连接

自定义路径

const socket = io('http://localhost/admin', {
  path: '/mypath'
});

socket使用自定义路径mypath连接到admin命名空间

请求地址如下：localhost/mypath/?EIO=3&transport=polling&sid=<id>

查询参数

const socket = io('http://localhost?token=abc');

// server-side
const io = require('socket.io')();

// middleware
io.use((socket, next) => {
  let token = socket.handshake.query.token;
  if (isValid(token)) {
    return next();
  }
  return next(new Error('authentication error'));
});

// then
io.on('connection', (socket) => {
  let token = socket.handshake.query.token;
  // ...

});

通过scoket.handshake获得握手细节信息

查询选项

const socket = io({
  query: {
    token: 'cde'
  }
});

查询内容可以在重新连接时更新

socket.on('reconnect_attempt', () => {
  socket.io.opts.query = {
    token: 'fgh'
  }
});

extraHeaders

仅在启用轮询时有效。使用websocket传输时，不会追加自定义header。这是因为websocket不支持自定义header

const socket = io({
  transportOptions: {
    polling: {
      extraHeaders: {
        'x-clientid': 'abc'
      }
    }
  }
});

// server-side
const io = require('socket.io')();

// middleware
io.use((socket, next) => {
  let clientId = socket.handshake.headers['x-clientid'];
  if (isValid(clientId)) {
    return next();
  }
  return next(new Error('authentication error'));
});

仅使用webscoket传输

默认情况下，先建立一个长轮询连接，然后升级至“更好”的传输（就像websocket）

const socket = io({
  transports: ['websocket']
});

// on reconnection, reset the transports option, as the Websocket
// connection may have failed (caused by proxy, firewall, browser, ...)
socket.on('reconnect_attempt', () => {
  socket.io.opts.transports = ['polling', 'websocket'];
});

自定义解析器

服务器和客户端需要使用同一种解析器方便解析

const parser = require('socket.io-msgpack-parser'); // or require('socket.io-json-parser')
const socket = io({
  parser: parser
});

// the server-side must have the same parser, to be able to communicate
const io = require('socket.io')({
  parser: parser
});

自签名证书

// server-side
const fs = require('fs');
const server = require('https').createServer({
  key: fs.readFileSync('server-key.pem'),
  cert: fs.readFileSync('server-cert.pem')
});
const io = require('socket.io')(server);
server.listen(3000);

// client-side
const socket = io({
  // option 1
  ca: fs.readFileSync('server-cert.pem'),

  // option 2. WARNING: it leaves you vulnerable to MITM attacks!
  rejectUnauthorized: false
});