Window: message event

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.

Bubbles No
Cancelable No
Interface MessageEvent
Event handler property onmessage


Suppose a script sends a message to a different browsing context, such as another <iframe>, using code like this:

const targetFrame =[1];
const targetOrigin = '';
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: ${}`);

Alternatively the listener could use the onmessage event handler property:

window.onmessage = (event) => {
    console.log(`Received message: ${}`);


Specification Status
HTML Living Standard Living Standard

Browser compatibility

BCD tables only load in the browser

See also