MessageChannel.port2 - Web API 接口参考 编辑

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。

语法

channel.port2;

值

表示通道第二个端口的一个MessagePort对象，该端口附加到通道另一端的上下文。

 

示例

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 = e.data;
}   

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).

Specifications

Specification	Status	Comment
HTML Living Standard port2	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!

• Desktop
• Mobile

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

• Using channel messaging