14.3 跨域 - postMessage

前端

a.html

<iframe src="http://localhost:4000/b.html" frameborder="0" id="frame" onload="load()"></iframe>
<script>
    function load() {
      const frame = document.getElementById('frame')
      frame.contentWindow.postMessage('我爱你', 'http://localhost:4000') // 要加上发送的域

      window.onmessage = e => {
        console.log(e.data)
      }
    }
</script>

b.html

<script>
    window.onmessage = e => {
      console.log(e.data)
      e.source.postMessage('我不爱你', e.origin)
    }
</script>

后端

a.js

let express = require('express')
let app  = express()
app.use(express.static(__dirname))
app.listen(3000)

b.js

let express = require('express')
let app  = express()
app.use(express.static(__dirname))
app.listen(4000)