Sends a cross-document message.

Syntax

object.postMessage(msg [, targetOrigin])

Parameters

msg	Required. A String that contains the message data.
targetOrigin	Optional. A String that specifies a target Uniform Resource Identifier (URI).

Return Value

No return value.

Remarks

Note  "*" is a valid value for targetOrigin.

The postMessage method allows cooperative text exchange between untrusted modules from different domains embedded within a page. It does so by ensuring a consistent and secure process for text-based data exchange.

When a script invokes this method on a window object, the browser sends an onmessage event to the target document on which the data property has been set to the value passed in msg.

When a target URI is passed into the method, it must have at least a protocol and a host specified. The message will only be sent if the target window has the same protocol and host as the specified target URI.

The postMessage method call does not return until the event listeners of the target document have finished executing.

Examples

If Document A contains a reference to the contentWindow property of Document B, script in Document A can send a message to Document B by calling the postMessage method as follows:

var o = document.getElementsByTagName('iframe')[0];
o.contentWindow.postMessage('Hello World');

The script in Document B can respond to the message by registering the onmessage event handler for incoming messages.

window.attachEvent('onmessage',function(e) {
    if (e.domain == 'example.com') {
        if (e.data == 'Hello World') {
            e.source.postMessage('Hello');
        } else {
            alert(e.data);
        }
    }
});

Standards Information

This method is defined in HTML 5 .

Applies To

window, Window Constructor

See Also

onmessage