coderef

postMessageBaseline · Widely available

The postMessage() global method sends cross-origin messages to windows and workers, including popups and iframes. Also known as cross-document messaging.

Supported in all major browsers for at least 30 months — safe to use without fallbacks. Baseline since Jul 29, 2015. Widely available since Jan 29, 2018.

How to use ↓Compare browsers

Browser support

DesktopChrome
1–1Not supported
2+Supportedsince May 21, 2009
Current: 155
Edge
12+Supportedsince Jul 29, 2015
Current: 154
Firefox
1–2Not supported
3+Supportedsince Jun 17, 2008
Current: 157
Safari
1–3.1Not supported
4+Supportedsince Jun 8, 2009
Current: 27
MobileChrome Android
18+Supportedsince Jun 27, 2012
Current: 155
Firefox Android
4+Supportedsince Mar 29, 2011
Current: 157
Safari iOS
1–3Not supported
3.2+Supportedsince Apr 3, 2010
Current: 27

How to use

This feature is Baseline widely available — use it freely, no fallback needed.

Example

Full syntax and examples are on MDN: message event.

Feature detection

JS · check before using
if ("DedicatedWorkerGlobalScope" in globalThis && "postMessage" in DedicatedWorkerGlobalScope.prototype) {
  // DedicatedWorkerGlobalScope.postMessage is available
}

Documentation (MDN)

Specification

Usage share

Sub-features

Support for each part of the feature (13). The overall table above shows when the whole feature works.

Sub-featureChromeEdgeFirefoxSafariChrome AndroidFirefox AndroidSafari iOS
DedicatedWorkerGlobalScope.message_event4123.541845
DedicatedWorkerGlobalScope.postMessage4123.541845
MessageEvent212341843.2
MessageEvent.MessageEvent161426618266
MessageEvent.data212341843.2
MessageEvent.lastEventId217341843.2
MessageEvent.origin212341843.2
MessageEvent.source212341843.2
Window.message_event6012946094
Window.postMessage212341843.2
Window.postMessage.transfer_parameter41220518204
Worker.message_event4123.541845
Worker.postMessage2123.541845