Is it possible to alter globally available JavaScript objects from within a Chrome browser extension? E.g., I want the extension to change what the window.navigator.platform property returns to the site.
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I created a question a few minutes ago here: How to modify Chrome Extension, which authenticates every user through Google's OAuth 2?
However, it seems like the CRX files are signed, which means I cannot modify the extension. However, I know exactly how the extension works. Basically I need to do call a function, while parsing it a string. Is that possible to do through my website? The function from the background.js could look like this:
function sendAlert(message) {
alert(message);
}
Is it possible to call sendAlert() from my website?
It's not possible to directly access an extension from a web page.
A web page can communicate with an extension in two cases:
the extension expects external connections via, for example, runtime.onMessageExternal.
the extension listens to DOM events of the page in its content script AND there's an event that triggers the behavior you need
I am working on a Chrome extension that needs to call a native application.
As per Google documentation, we are using the chrome.runtime.connectNative method.
However in our extension, it seems that the chrome.runtime object has no method 'connectNative'. When we display the list of methods of the chrome.runtime object, we get the following list (printed by console.log("" + Object.getOwnPropertyNames(chrome.runtime));
getManifest,getURL,reload,requestUpdateCheck,connect,sendMessage,onConnect,onMessage,id
We are using Chrome 31.0.1650.63 on MacOS X 10.8.5 . We have also tried with Chrome Canary (version 34.0.1767.0 canary), we have the same error, with a slightly different list of methods for chrome.runtime:
getManifest,getURL,setUninstallUrl,reload,requestUpdateCheck,connect,sendMessage,onConnect,onMessage,id
So, in both cases (regular Chrome and Chrome Canary), we don't have the 'connectNative' method.
This does not seem to be a permissions problem, our extension manifest does have "nativeMessaging" in the permissions attribute. When we click on the permissions link in the Chrome extension settings, we can see that the extension can "communicate with cooperating native applications".
(sorry I couldn't post screenshots or the full manifest, StackOverflow won't let me paste things that even remotely look like I'm posting an image since I don't have enough reputation....)
Are we missing something ?
The list of properties of chrome.runtime you are getting indicates that your code is running as a content script. Most chrome.* APIs are not available to content scripts. They can only be used from background or event pages, popups, or other extension views you define. So you can use regular extension messaging from your content script to a background or event page, which in its turn can call your native app.
I would like to modify my extension's popup dynamically (at run-time). And want to specify a custom popup HTML file that's loaded from my server.
In Firefox, I can easily accomplish this with XUL overlays which I can specify at run-time.
And document.loadOverlay() does allow me to specify a 'remote' URL for the overlay.
Is the same possible in Chrome?
I've been playing with chrome.browserAction.setPopup( details ) API, but it seems that the details.popup param must specify a local file, and not a remote URL.
I have answered this exact same question on the Chromium-Extensions mailinglist.
There is no API to load external popups but you can do that with plain JavaScript. What you could do (I have done that in the past):
Use an iframe + extension messaging within the popup. The iframe
points to some external url not hosted in the extension.
Use templates (jQuery templates example), load those template files to
your background page, and just use them to construct your popup.
Download the html contents using XHR and load them within the popup
by constructing the DOM.
I usually use the template approach, but I use the popup iframe approach when I want to manage the entire popup in the server side so I don't have to push updates to the extension gallery. I am not a fan of downloading the HTML contents, templating seems safer.
Hope this helped!
I come from Chrome extensions, so I'm used to defining when a file should be injected by setting run_at, e.g., to document_start for injection before DOM construction. Is there an equivalent for Firefox addons?
Yes, the equivalent would be the content-document-global-created notification. An extension can add an observer for that notification and then do something with the window - like injecting a content script. See How to override JS function from a firefox extension? for one example of using this notification.
If you use the Add-on SDK it will do this job for you. The page-mod package supports a contentScriptWhen parameter - you can use "start" as its value and the content script will be injected before any page scripts get a chance to run.
I was wondering with Google Chrome's extension API, is it possible to extract memory usage data for each tab and use it in a popup? I know there is this extension https://chrome.google.com/extensions/detail/mmbijkbkjlefoimjopcojbkpnmljahlh but all it does is simply open the about:memory tab. I was thinking maybe there was a way to "parse" the about:memory tab and use it for my extension. Or am I delusional and this is not possible?
There is no such API and chrome:// scheme is forbidden for extensions so you can't parse that page either...
XMLHttpRequest calls to chrome:// are not allowed
Content scripts are not injected under chrome://
The chrome.processes API can be used to obtain the same data that the Task Manager uses: https://developer.chrome.com/extensions/processes