MessagePort.start() - Web APIs 编辑

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 MessageChannel.onmessage.

Note:

Syntax

port.start()

Returns

Void.

Parameters

None.

Example

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

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:

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

channel.port1.start();

Specifications

Browser compatibility

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See also

• Using channel messaging