MessageChannel接口的 port2 是一个只读属性,返回消息通道的第二个端口,该端口连接到通道另一端的上下文,也就是发送消息时的目的地。

Note: 此特性在 Web Worker 中可用






如下代码所示,通过MessageChannel.MessageChannel构造函数创建了一个新的通道。当IFrame加载完毕,我们使用MessagePort.postMessage (en-US)将一条消息以及port2传递给IFrame。handleMessage处理程序响应从IFrame发回的消息(使用 MessagePort.onmessage),将其放入段落中。MessageChannel.port1已经监听,以检测消息何时到达。

var channel = new MessageChannel();
var para = document.querySelector('p');

var ifr = document.querySelector('iframe');
var otherWindow = ifr.contentWindow;

ifr.addEventListener("load", iframeLoaded, false);

function iframeLoaded() {
  otherWindow.postMessage('Hello from the main page!', '*', [channel.port2]);

channel.port1.onmessage = handleMessage;
function handleMessage(e) {
  para.innerHTML =;

有关完整的运行示例,请参阅我们在GitHub的 channel messaging basic demo  (run it live too).


Specification Status Comment
HTML Living Standard
Living Standard  

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help! (en-US)
Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 4 (Yes) 41 (41) 10.0 10.6 5
Available in workers (Yes) ? 41 (41) (Yes) (Yes) (Yes)
Feature Android Chrome for Android Edge Firefox Mobile (Gecko) Firefox OS (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support 4.4 4 (Yes) 41.0 (41) (Yes) 10.0 11.5 5.1
Available in workers (Yes) (Yes) ? 41.0 (41) (Yes) (Yes) (Yes) (Yes)

See also