14.6 socket跨域

<script>
    // 高级api 不兼容 socket.io
    // http单向的，socket是双向的，传输都靠tcp
    let socket  = new WebSocket(‘ws://localhost:3000‘)
    socket.onopen = () => { // 多个页面通信就是 先发给服务器，服务器再发给另一个页面
       socket.send(‘我爱你‘)
    }
    socket.onmessage = e => {
      console.log(e.data)
    }
</script>

let express = require(‘express‘)
let app = express()
let WebSocket = require(‘ws‘)
let wss = new WebSocket.Server({port:3000 })
wss.on(‘connection‘, ws => {
  ws.on(‘message‘, data => {
    console.log(data)
    ws.send(‘我不爱你‘)
   })
})