Channel Messaging API

The Channel Messaging API allows two separate scripts running in different browsing contexts attached to the same document (e.g., two IFrames, or the main document and an IFrame, two documents via a SharedWorker, or two workers) to communicate directly, passing messages between one another through two-way channels (or pipes) with a port at each end.

주의: 이 기능은 Web Worker에서 사용할 수 있습니다

Channel messaging concepts and usage

A message channel is created using the MessageChannel() (en-US) constructor. Once created, the two ports of the channel can be accessed through the MessageChannel.port1 (en-US) and MessageChannel.port2 (en-US) properties (which both return MessagePort (en-US) objects.) The app that created the channel uses port1, and the app at the other end of the port uses port2 — you send a message to port2, and transfer the port over to the other browsing context using window.postMessage along with two arguments (the message to send, and the object to transfer ownership of, in this case the port itself.)

When these transferable objects are transferred, they are 'neutered' on the previous context — the one they previously belonged to. For instance a port, when is sent, cannot be used anymore by the original context. Note that the only two objects that can currently be transferred are ArrayBuffer and MessagePort (en-US).

The other browsing context can listen for the message using MessagePort.onmessage (en-US), and grab the contents of the message using the event's data attribute. You could then respond by sending a message back to the original document using MessagePort.postMessage (en-US).

When you want to stop sending messages down the channel, you can invoke MessagePort.close (en-US) to close the ports.

Find out more about how to use this API in Using channel messaging.

Channel messaging interfaces

MessageChannel (en-US)
Creates a new message channel to send messages across.
MessagePort (en-US)
Controls the ports on the message channel, allowing sending of messages from one port and listening out for them arriving at the other.
PortCollection
An array of MessagePorts; an experimental solution to allow broadcasting of a message to multiple ports simultaneously.

Examples

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'Channel messaging' in that specification.
Living Standard  

Browser compatibility

MessageChannel

If you're able to see this, something went wrong on this page.

MessagePort

If you're able to see this, something went wrong on this page.

See also