chrome.extension.onMessage is undefined

Question

I have a simple plugin that just does something like this:

chrome.extension.onMessage.addListener(function(msg, _, sendResponse) {
    log("Got message from background page: " + msg);
});

unfortunately when my panel is loaded the following error is shown:

TypeError: Cannot call method 'addListener' of undefined

and according to my tests chrome.extension.onMessage is undefined

According to this page http://code.google.com/chrome/extensions/messaging.html I should be able to access this chrome API from my page so it has to be something small that I am missing here...

Answer 1

Please note methods chrome.extension.onRequest and chrome.extension.sendRequest, as originally suggested in this answer, are deprecated as of Chrome 33.

---

You should use

chrome.extension.onRequest

instead of

chrome.extension.onMessage

And in background page or any other extension scripts:

chrome.tabs.sendRequest

instead of

chrome.tabs.sendMessage

( the documentation is outdated... alert to google team ;) )