<!DOCTYPE html><htmllang="en"><head><metacharset="UTF-8"><title>Title</title></head><body><p>這是B頁面</p><divid="box"></div><script>// 監聽a
window.onmessage=function(ev){var h1 = document.createElement('h1')
h1.innerHTML ='這是b,收到了a的消息:'+ ev.data
document.getElementById('box').appendChild(h1)// B發送給a
ev.source.postMessage('hello a, i am b, i receiver your message', ev.origin)}</script></body></html>