Window: message event
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since August 2017.
The message event is fired on a Window object when the window receives a message, for example from a call to Window.postMessage() from another browsing context.
This event is not cancellable and does not bubble.
Syntax
Use the event name in addEventListener():
addEventListener("message", (event) => { })
Alternatively, assign to the event handler property of the interface:
onmessage = (event) => { }
Event type
A MessageEvent. Inherits from Event.
Examples
Suppose a script sends a message to a different browsing context, such as another <iframe>, using code like this:
const targetFrame = window.top.frames[1];
const targetOrigin = "https://example.org";
const windowMessageButton = document.querySelector("#window-message");
windowMessageButton.addEventListener("click", () => {
targetFrame.postMessage("hello there", targetOrigin);
});
The receiver can listen for the message using addEventListener() with code like this:
window.addEventListener("message", (event) => {
console.log(`Received message: ${event.data}`);
});
Alternatively the listener could use the onmessage event handler property (but note that this replaces other event listeners added using onmessage, if any):
window.onmessage = (event) => {
console.log(`Received message: ${event.data}`);
};
Specifications
| Specification |
|---|
| HTML> # event-message> |
| HTML> # handler-window-onmessage> |
Browser compatibility
See also
- Related events:
messageerror. Window.postMessage().