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MessagePort: start() method

The start() method of the MessagePort interface starts the sending of messages queued on the port. This method is only needed when using EventTarget.addEventListener; it is implied when using onmessage.

Note: This feature is available in Web Workers

Syntax

js

start()

Parameters

None.

Return value

None (undefined).

Examples

In the following code block, you can see a handleMessage handler function, run when a message is sent back to this document using onmessage:

js

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

Another option would be to do this using EventTarget.addEventListener, however, when this method is used, you need to explicitly call start() to begin the flow of messages to this document:

js

channel.port1.addEventListener("message", handleMessage, false);
function handleMessage(e) {
  para.innerHTML = e.data;
  textInput.value = "";
}

channel.port1.start();

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
start 2 12 41 10 10.6 5 4.4 18 41 11 4.2 1.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/MessagePort/start