The MessageChannel
interface of the Channel Messaging API allows us to create a new message channel and send data through it via its two MessagePort
properties.
Note: This feature is available in Web Workers.
Properties
MessageChannel.port1
Read only- Returns port1 of the channel.
MessageChannel.port2
Read only- Returns port2 of the channel.
Constructor
MessageChannel()
-
Returns a new
MessageChannel
object with two newMessagePort
objects.
Example
In the following example, you can see a new channel being created using the MessageChannel.MessageChannel
constructor.
When the IFrame has loaded, we register an onmessage
handler for MessageChannel.port1
and transfer MessageChannel.port2
to the IFrame using the window.postMessage
method along with a message.
When a message is received back from the IFrame, the onMessage
function simply outputs the message to a paragraph.
var channel = new MessageChannel(); var output = document.querySelector('.output'); var iframe = document.querySelector('iframe'); // Wait for the iframe to load iframe.addEventListener("load", onLoad); function onLoad() { // Listen for messages on port1 channel.port1.onmessage = onMessage; // Transfer port2 to the iframe iframe.contentWindow.postMessage('Hello from the main page!', '*', [channel.port2]); } // Handle messages received on port1 function onMessage(e) { output.innerHTML = e.data; }
For a full working example, see our channel messaging basic demo on Github (run it live too).
Specifications
Specification | Status | Comment |
---|---|---|
HTML Living Standard The definition of 'Message channels' in that specification. |
Living Standard |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
MessageChannel | Chrome Full support 4 | Edge Full support 12 | Firefox Full support 41 | IE Full support 10 | Opera Full support 10.6 | Safari Full support 5 | WebView Android Full support 4.4 | Chrome Android Full support 18 | Firefox Android Full support 41 | Opera Android Full support 11 | Safari iOS Full support 5.1 | Samsung Internet Android Full support 1.0 |
MessageChannel() constructor | Chrome Full support 4 | Edge Full support 12 | Firefox Full support 41 | IE Full support 10 | Opera Full support 10.6 | Safari Full support 5 | WebView Android Full support 4.4 | Chrome Android Full support 18 | Firefox Android Full support 41 | Opera Android Full support 11 | Safari iOS Full support 5.1 | Samsung Internet Android Full support 1.0 |
port1 | Chrome Full support 4 | Edge Full support 12 | Firefox Full support 41 | IE Full support 10 | Opera Full support 10.6 | Safari Full support 5 | WebView Android Full support 4.4 | Chrome Android Full support 18 | Firefox Android Full support 41 | Opera Android Full support 11 | Safari iOS Full support 5.1 | Samsung Internet Android Full support 1.0 |
port2 | Chrome Full support 4 | Edge Full support 12 | Firefox Full support 41 | IE Full support 10 | Opera Full support 10.6 | Safari Full support 5 | WebView Android Full support 4.4 | Chrome Android Full support 18 | Firefox Android Full support 41 | Opera Android Full support 11 | Safari iOS Full support 5.1 | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support