I'm trying to create a page action extension in chrome. I have an html page corresponding to the popup that gets displayed on clicking the page action. I have included a script file popup.js in this html page. From this page I'm trying to send a message to a background js file background.js. The problem is that I'm calling sendRequest only once from popup.js but I'm receiving it in the background page multiple times. I'm doing a file action there which results in script errors because of concurrent access. I'm pasting the code related to message passing here
extension file - popup.js
chrome.extension.sendRequest({"intent" : "read"}, function (message) {
console.log(message);
});
background page - background.js
(function(){
var fileName = "credentials.txt";
var fileSystem;
function checkUrl(tabId, changeInfo, tab) {
if(/https?:\/\/.*?\/olc/.test(tab.url)) {
chrome.pageAction.show(tabId);
chrome.extension.onRequest.addListener(function (request, sender, callback) {
callback("printed");
});
}
}
chrome.tabs.onUpdated.addListener(checkUrl);
})();
The listener is called 4 times in this case. The callback will be called the first time. The next 3 times it gives an error saying Could not send response: Cannot send a response more than once per chrome.extension.onRequest listener per document (message was sent by extension kaejjpmlibijbgbgcfodphlkcjjkmjlk). Can anyone help me with this?
They're supposed to work only once.
You can either use the long-lived messaging system or reattach the same handler over and over again upon receiving the message from the content script.
Use chrome.extension.getBackgroundPage(). You will have access to background page from yor popup.
Or write to localStorage and use listener.
window.addEventListener('storage', function (e) {}, false);
You will have problems with memory leak if you will use chrome.extension.sendRequest for comunication between popup and background.html.
Related
Summary: I need to find a way to accomplish with programmatic injection the same exact behaviour as using content_scripts > matches with "all_frames": true on a manifest. Why? because it is the only way I've found of injecting iframe's content in an extension page without having Cross-Origin errors.
I'm moving to optional_permissions on a Chrome extension and I'm on a dead end.
What I want:
Move this behaviour to optional_permissions in order to be able to add more hosts in the future. With the current code, by adding one new host on content_scripts > matches the extension is disabled by Chrome.
For the move, I removed content_scripts in the manifest and I added "optional_permissions": ["*://*/"],. Then, I successfully implemented a dialog asking new permissions to the user with chrome.permissions.request.
As I said before, the problem is how to inject the iframe's content in an extension page.
What I've tried:
chrome.declarativeContent.RequestContentScript (mentioned here) with allFrames: true. I can only see the script running if I enter the URL directly, nothing happens when that URL is set in an iframe.
chrome.tabs.onUpdated: url is undefined for an extension page. Also, the iframe url is not detected.
Call chrome.tabs.executeScript with allFrames: true as soon as I load the first iframe. By doing this I get an exception Cannot access contents of the page. Extension manifest must request permission to access the respective host. and the "respective host" is chrome-extension://, which is not a valid host if you want to add it to the permissions.
I'm lost. I couldn't find a way to simulate the same behaviour as content_scripts > matches with programmatic injection.
Note: using webNavigation API is not an option since the extension is live and it has thousands of users. Because of this, I can not use the frameId property for executeScript. Thus, my only option with executeScript was to inject all frames but the chrome-extension host issue do not let me continue.
Update: I was able to accomplish what I wanted but only on an HTTP host. I used chrome.tabs.executeScript (option 3).
The question remains on how to make this work on an extension page.
You cannot run content scripts in any extension page, including your own.
If you want to run code in a subframe of your extension page, then you have to use frameId. There are two ways to do this, with and without webNavigation.
I've put all code snippets in this answer together (with some buttons to invoke the individual code snippets) and shared it at https://robwu.nl/s/optional_permissions-script-subframe.zip
To try it out, download and extract the zip file, load the extension at chrome://extensions and click on the extension button to open the test page.
Request optional permissions
Since the goal is to programmatically run scripts with optional permissions, you need to request the permission. My example will use example.com.
If you want to use the webNavigation API too, include its permission in the permission request too.
chrome.permissions.request({
// permissions: ['webNavigation'], // uncomment if you want this.
origins: ['*://*.example.com/*'],
}, function(granted) {
alert('Permission was ' + (granted ? '' : 'not ') + 'granted!');
});
Inject script in subframe
Once you have a tab ID and frameId, injecting scripts in a specific frame is easy. Because of the tabId requirement, this method can only work for frames in tabs, not for frames in your browserAction/pageAction popup or background page!
To demonstrate that code execution succeeds, my examples below will call the next injectInFrame function once the tabId and frameId is known.
function injectInFrame(tabId, frameId) {
chrome.tabs.executeScript(tabId, {
frameId,
code: 'document.body.textContent = "The document content replaced with content at " + new Date().toLocaleString();',
});
}
If you want to run code not just in the specific frame, but all sub frames of that frame, just add allFrames: true to the chrome.tabs.executeScript call.
Option 1: Use webNavigation to find frameId
Use chrome.tabs.getCurrent to find the ID of the tab where the script runs (or chrome.tabs.query with {active:true,currentWindow:true} if you want to know the current tabId from another script (e.g. background script).
After that, use chrome.webNavigation.getAllFrames to query all frames in the tab. The primary way of identifying a frame is by the URL of the page, so you have a problem if the framed page redirects elsewhere, or if there are multiple frames with the same URL. Here is an example:
// Assuming that you already have a frame in your document,
// i.e. <iframe src="https://example.com"></iframe>
chrome.tabs.getCurrent(function(tab) {
chrome.webNavigation.getAllFrames({
tabId: tab.id,
}, function(frames) {
for (var frame of frames) {
if (frame.url === 'https://example.com/') {
injectInFrame(tab.id, frame.frameId);
break;
}
}
});
});
Option 2: Use helper page in the frame to find frameId
The option with webNavigation looks simple but has two main disadvantages:
It requires the webNavigation permission (causing the "Read your browsing history" permission warning)
The identification of the frame can fail if there are multiple frames with the same URL.
An alternative is to first open an extension page that sends an extension message, and find the frameId (and tab ID) in the metadata that is made available in the second parameter of the chrome.runtime.onMessage listener. This code is more complicated than the other option, but it is more reliable and does not require any additional permissions.
framehelper.html
<script src="framehelper.js"></script>
framehelper.js
var parentOrigin = location.ancestorOrigins[location.ancestorOrigins.length - 1];
if (parentOrigin === location.origin) {
// Only send a message if the frame was opened by ourselves.
chrome.runtime.sendMessage(location.hash.slice(1));
}
Code to be run in your extension page:
chrome.runtime.onMessage.addListener(frameMessageListener);
var randomMessage = 'Random message: ' + Math.random();
var f = document.createElement('iframe');
f.src = chrome.runtime.getURL('framehelper.html') + '#' + randomMessage;
document.body.appendChild(f);
function frameMessageListener(msg, sender) {
if (msg !== randomMessage) return;
var tabId = sender.tab.id;
var frameId = sender.frameId;
chrome.runtime.onMessage.removeListener(frameMessageListener);
// Note: This will cause the script to be run on the first load.
// If the frame redirects elsewhere, then the injection can seemingly fail.
f.addEventListener('load', function onload() {
f.removeEventListener('load', onload);
injectInFrame(tabId, frameId);
});
f.src = 'https://example.com';
}
I've made an extension who's purpose is to redirect urls.
I.e: www.google.com becomes: www.mysite.com/?url=www.google.com
I came across this post:
How to modify current url location in chrome via extensions
The problem I'm having is that the url's are both processed. The tab initially loads up google.com and only after it's finished my request is shown ( www.mysite.com/?url=www.google.com).
Is there any way to stop the initial request from being processed?
Something like:
chrome.tabs.onUpdated.addListener(function(tabId,obj,tab){
update.stop() // ??????????? Here I'm missing...
chrome.tabs.update(tabId,{url:....}, function callback); // My update stuff..
});
Thoughts?
thank you all.
You're looking for the webNavigation API.
You can register listeners to handle user navigation by modifying or blocking the request on the fly.
In the example below, when a user navigate to www.google.com, before the page even start loading onBeforeNavigate is fired and you can redirect the user to the CSS validation page for that URL:
chrome.webNavigation.onBeforeNavigate.addListener((details) => {
if(details.url.indexOf("www.google.com") !== -1)) {
chrome.tabs.update(details.tabId, {
url: "https://jigsaw.w3.org/css-validator/validator?uri=" + details.url
});
}
});
Remember to add the "webNavigation" permission to your extension manifest to get this functionality enabled.
chrome.tabs.onUpdated is fired two times per tab load - once a tab starts loading, and another time when it finishes loading. If you attach your update to the tab start loading event then it should work relatively quickly. You will still see original url being loaded for a brief moment, but it won't wait until it finishes, as you are describing.
chrome.tabs.onUpdated.addListener(function(tabId,obj,tab){
if(obj.status == "loading") {
chrome.tabs.update(tabId,{url:....}, function callback);
}
});
I don't think there is a more efficient solution at the moment.
I'm trying to develop (for the moment!) a simple chrome extension using the message exchanging API.
My contentscript ask the background page for its url, and wait the background answer.
However, my contentscrpt never get the answer. Why? Thanks for your answer.
content_script.js
/**
* Retrieve the url or the page currently visited.
*/
chrome.extension.sendRequest({'action' : 'getUrl'}, function(response) {
alert(response.url);
});
background.html
...
function onRequest(request, sender, callback) {
sendResponse({'url' : sender.tab.url});
};
chrome.extension.onRequest.addListener(onRequest);
Your onRequest function has the final parameter named callback, but you call sendResponse in it. Assuming this is what your actual code looks like, you'll need to make the two names the same. If you inspect the background page in the developer tools, you should see a JavaScript exception about sendResponse being undefined.
I'm building a chrome extension and trying to get data from twitter and then pass that to my contentscript. I'm having a lot of problems with this. I'm able to get the data from the remote site but can't seem to pass it to my content script. I have a listener for when i click the icon using chrome.extension.onclick.addlistener(functionname);. This gets the data. The Problem is once i get the data, i need to send a response to the request from my content script. So i'm also calling chrome.extension.Onrequest.addlistener(functioname);. Before i go on trying to figure out what's wrong with the code, is it allowed to have 2 listeners for 2 separate events in the same page as i've done or can you only have one listener?
I know this is a crazy old question, but I came across this while experiencing a related issue and wanted to share in case it was useful for anyone else.
Make sure you're only calling the sendResponse method at most once if you do have multiple listeners. From the docs:
sendResponse: Function to call (at most once) when you have a response.
The argument should be any JSON-ifiable object. If you have more than
one onMessage listener in the same document, then only one may send a
response. This function becomes invalid when the event listener
returns, unless you return true from the event listener to indicate
you wish to send a response asynchronously (this will keep the message
channel open to the other end until sendResponse is called).
If you do a quick search on Stackoverflow, you will see many examples with code on how to send messages from background page to content script:
https://stackoverflow.com/search?tab=relevance&q=content%20script%20background%20page
For more information how to do this, you can follow the docs themselves, they have great examples:
http://code.google.com/chrome/extensions/messaging.html
From the documentation (copy paste):
content_script.cs
chrome.extension.onRequest.addListener(function(request, sender, sendResponse) {
if (request.greeting == "hello")
sendResponse({farewell: "goodbye"});
else
sendResponse({}); // snub them.
});
background.html
chrome.tabs.getSelected(null, function(tab) {
chrome.tabs.sendRequest(tab.id, {greeting: "hello"}, function(response) {
console.log(response.farewell);
});
});
The fact that you have created a listener for the onClick event and a listener for the onRequest event is not a problem. You can tell by typing out chrome.onClick and chrome.OnRequest at the console for the background page; you'll see they are each instances of type 'chrome.Event'.
If you think about it, if you were only able to create one listener it would greatly reduce your ability to write something useful since you could only respond to one of { onrequest, onclick, ontabchange, onconnect, ondisconnect, etc. }
In Google Chrome's extension developer section, it says
The HTML pages inside an extension
have complete access to each other's
DOMs, and they can invoke functions on
each other. ... The popup's contents
are a web page defined by an HTML file
(popup.html). The popup doesn't need
to duplicate code that's in the
background page (background.html)
because the popup can invoke functions
on the background page
I've loaded and tested jQuery, and can access DOM elements in background.html with jQuery, but I cannot figure out how to get access to DOM elements in popup.html from background.html.
can you discuss why you would want to do that? A background page is a page that lives forever for the life time of your extension. While the popup page only lives when you click on the popup.
In my opinion, it should be refactored the other way around, your popup should request something from the background page. You just do this in the popup to access the background page:
chrome.extension.getBackgroundPage()
But if you insist, you can use simple communication with extension pages with sendRequest() and onRequest. Perhaps you can use chrome.extension.getViews
I understand why you want to do this as I have run into the problem myself.
The easiest thing I could think of was using Google's method of a callback - the sendRequest and onRequest methods work as well, but I find them to be clunky and less straightforward.
Popup.js
chrome.extension.getBackgroundPage().doMethod(function(params)
{
// Work with modified params
// Use local variables
});
Background.html
function doMethod(callback)
{
if(callback)
{
// Create/modify params if needed
var params;
// Invoke the callback
callback(params);
}
}
As other answers mention, you can call background.js functions from popup.js like so:
var _background = chrome.extension.getBackgroundPage();
_background.backgroundJsFunction();
But to access popup.js or popup.html from background.js, you're supposed to use the messages architecture like so:
// in background.js
chrome.runtime.sendMessage( { property: value } );
// in popup.js
chrome.runtime.onMessage.addListener(handleBackgroundMessages);
function handleBackgroundMessages(message)
{
if (message.property === value)
// do stuff
}
However, it seems that you can synchronously access popup.js from background.js, just like you can synchronously access the other way around. chrome.extension.getViews can get you the popup window object, and you can use that to call functions, access variables, and access the DOM.
var _popup = chrome.extension.getViews( { type: 'popup' } )[0];
_popup.popupJsFunction();
_popup.document.getElementById('element');
_popup.document.title = 'poop'
Note that getViews() will return [] if the popup is not open, so you have to handle that.
I'm not sure why no one else mentioned this. Perhaps there's some pitfalls or bad practices to this that I've overlooked? But in my limited testing in my own extension, it seems to work.