opera.extension.onmessage

By Opera Software

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Description:

This event listener is invoked when a message is received from an injected script, popup or preferences page. The event's source is a messagePort to the connecting environment.

Example:

//
// The background process ('/background.js').
//

opera.extension.onmessage = function(event) {
  // Get the message content from the event's data property
  var message = event.data;
};

This article is licensed under a Creative Commons Attribution 3.0 Unported license.

Comments

metude

Friday, November 2, 2012

Here's a more description from spadija ( http://my.opera.com/spadija )

Messaging is just a way to communicate between the parts of an extension.
The background script, injected scripts, popup, etc. can all listen for
messages sent to them and send messages to each other.

// Here I set a function to be called whenever the background script gets
a message
opera.extension.onmessage = function(e) {
// "e" holds information about the message that was sent.
// for example, "e.source" is a reference to whatever sent the message
// and "e.data" is the data sent with the message.

// Here the data is the URL we want the popup to switch to.
opera.contexts.toolbar[0].popup.href = e.data;
}

// In the popup, this sends a message to the background script.
// The data sent with the message is the new popup URL.
// When this is run, the background script's "onmessage" function gets
called,
// and the "data" property of its first parameter will be
"http://some-url".
opera.extension.postMessage('http://some-url');