Communication between scripts in Chrome Extension - javascript

I know there are many variations of this question already in existence here, but none of them seem to work for me.
Details:
I'm writing an extension that pulls some email data from emails you send in gmail. In order to achieve this I am using this version of Gmailr https://github.com/joscha/gmailr.
In effect, I have three content scripts: Gmailr.js and main.js (which are pretty much identical to those in the link above) allow me to pull out the information I'm looking for. Then content.js I use to send a message to the background page of the extension.
The problem is that from gmailr.js and main.js I cannot use any of the Chrome APIs, and I'm not really sure why, so I can't send messages from these back to the background page.
That is why I made content.js which can communicate with the background page. However, it does not seem to be able to see anything the other content scripts do. For example, main.js inserts a div at the top of the page. When I try to attach an event listener to a button in this div from content.js, I am told that no such element exists.
How can I get the data pulled out by main.js to be seen by content.js? (I also tried to put the data in local storage, then trigger a custom event listener to tell content.js to read local storage, but no luck because they don't seem to be able to hear each other's event being triggered).
Any insight or alternatives are much appreciated.
(I can post code if necessary, but it's fragmented and long)
My manifest file:
{
"manifest_version": 2,
"name": "Email extractor",
"description": "Extracts data from emails",
"version": "1.0",
"background": {
"script": "background.js"
},
"content_scripts": [
{
"matches": [
"*://mail.google.com/*",
"*://*/*"
],
"js": [
"lib/yepnope.js/yepnope.1.5.4-min.js",
"lib/bootstrap.js",
"main.js",
"gmailr.js",
"content.js"
],
"css": [
"main.css"
],
"run_at": "document_end"
}
],
"permissions": [
"tabs",
"storage",
"background",
"*://mail.google.com/*",
"*://*/*"
],
"browser_action": {
"default_icon": "img/icon.png",
"default_popup": "popup.html"
},
"web_accessible_resources" : [
"writeForm.js",
"disp.js",
"/calendar/jsDatePick.min.1.3.js",
"/calendar/jsDatePick_ltr.min.css",
"lib/gmailr.js",
"lib/jquery-bbq/jquery.ba-bbq.min.js",
"content.js",
"main.js",
"background.js"
]
}
This is main.js:
Gmailr.init(function(G) {
sender = G.emailAddress();
G.insertTop($("<div id='gmailr'><span></span> <span id='status'></span>)");
el = document.getElementById("testid");
el.addEventListener('click', mg, false);
var status = function(msg) {
G.$('#gmailr #status').html(msg); };
G.observe(Gmailr.EVENT_COMPOSE, function(details) {
....
status(" user: " + user);
console.log('user:', user);
//now try to send a message to the background page
//this always returns the error that method sendMessage does not exist for undefined
chrome.runtime.sendMessage({greeting: "test from gmailr"}, function(response) {
console.log("did it send?");
});
});
});
gmailr.js is quite long and is also not my own code but it can be seen here: http://pastebin.com/pK4EG9vh

Hi perhaps 3 likely reason to your problem :
The way you send messages to bgp from main.js and gmailr.js are perhaps wrong because you must arrive to communicate from any content script to your bgp. (in your manifest content script key the gmailr.js is missing). Show us your code it would help.
You seems to have a problem with the moment you search from content.js to access to the element created in main.js. Do you try to access your element with the jQuery $("").on() method ? A simple test must be to declare a function in one cs and to use it in another. If it's not working it's a manifest problem. The order you declare .js file in manifest content script key is important also.
try to in the manifest content script array "run_at":"document_end"
Hope it help !

Related

Firefox Extension / Webextensions: Why doesn't the MDN example of Connection Based Messaging work?

This is the first time I read about writing Firefox extensions.
What I need is obviously only viable via WebExtensions and both a background and a contentscript. I actually only want to write all open tabs as links in a new tab and then File->Save it. Another alternative Idea was to put it into a JSON Object and save that through a dialog, then I probably could even spare the contentscript but I haven't found anything in the API to download a JSON Object via asking the user to download it via Download Dialog.
Whatever. I think I need to communicate with the content-script then.
I tried to run the following example, but it is not working. When I load the manifest file and open the debugger for extensions, it doesn't log anything and nothing has happened except that the variables myPort and portFromCS seem to be declared without any value.
https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_scripts#connection-based_messaging
// manifest.json
{
"manifest_version": 2,
"name": "Save Open Tabs",
"version": "1.0",
"description": "Save my tabs",
"background": {
"scripts": ["background.js"]
},
"content_scripts": [
{
"matches": ["*://*/*"],
"js": ["content.js"]
}
],
"permissions": [
"activeTab",
"tabs"
]
}
// content.js
let myPort=browser.runtime.connect({name:"port-from-cs"});
myPort.postMessage({greeting: "hello from content script"});
myPort.onMessage.addListener((m) => {
console.log("In content script, received message from background script: ");
console.log(m.greeting);
});
// background.js
let portFromCS;
function connected(p) {
portFromCS = p;
portFromCS.postMessage({greeting: "hi there content script!"});
portFromCS.onMessage.addListener((m) => {
portFromCS.postMessage({greeting: "In background script, received message from content script:" + m.greeting});
});
}
browser.runtime.onConnect.addListener(connected);
Why doesn't the example work? Maybe wrong URL matching in the manifest file?

Content script not executing in new window

I am trying to create a Chrome extension that, when clicked, opens a new incognito window and performs some DOM action on it. These are the files I'm using:
manifest.json
{
"manifest_version": 2,
"name": "SampleExtension",
"description": "",
"version": "1.0",
"incognito": "spanning",
"browser_action": {
"default_icon": "icon.png",
"default_popup": "popup.html"
},
"content_scripts": [
{
"matches": ["http://www.google.com"],
"js": ["myscript.js"]
}
],
"permissions": [
"tabs",
"activeTab",
"http://www.google.com"
]
}
popup.js
chrome.windows.create({
"url": "http://www.google.com",
"focused": true,
"incognito": true
});
chrome.tabs.executeScript(null, {
"file": "myscript.js",
"run_at": "document_end",
"all_frames": true
});
myscript.js
document.querySelector('a[target]').click();
The extension opens the new window, but my content script doesn't seem to be executing. Any thoughts?
Edit: Added "incognito": "spanning" to the manifest. Still doesn't work, however.
First of all, I understand that you have enabled to run in Incognito Mode. Extensions are disabled by default and, hence, it would not run otherwise.
Secondly, your match pattern needs to end with a slash:
"matches": ["http://www.google.com/"],
Thirdly, Google will redirect you to its https version, hence I would improve the match pattern like this:
"matches": ["*://www.google.com/"],
Still, it didn't work for me as I was redirected to my local Google domain. Hence, I had to do add more:
"matches": [
"*://www.google.com/*",
"*://www.google.com.sg/*"
],
Also, I added the final wildcard, because Google was adding some ?urlParams that I had to match too. And this made it work. Note that I tried with other pages like "*://www.stackoverflow.com/*", and it was easier than Google :)
In case your Google page was just a test, I'd advise to use some less redirected pages to test with.
A final note: I do not think it's possible to use the wildcard for the domain (I tried). However, you can request all the main domains, or request all_pages and then add the logic for Google only on my_script.js to decide whether to execute the action or not. (However, this last piece is not ideal).
Edit post comments:
It seems your function fails because the element is not loaded yet. An easy way to solve this is by doing an interval which checks whether the element is on the page. When it finds it, clicks it and removes the interval.
// Function which clicks element if existing and clears interval after doing it.
var clickLink = function() {
if (document.querySelectorAll('a[target]').length > 0) {
clearInterval(waitAndClick); // stop interval
document.querySelector('a[target]').click(); // click element.
}
}
// Run click function every second, until it clicks it.
var waitAndClick = setInterval(clickLink, 1000);

Communication between background.js and content-script? Response is UNDEFINED

From content-script:
chrome.runtime.sendMessage({ type: "getFormatOption" }, function (response) {
return response === 'csv';
});
I have inspected in console: the value, which is used in SendResponse() from background.js method is OK. The problem is that response is always UNDEFINED. What am I doing wrong?
background.js:
chrome.runtime.onMessage.addListener(
function (message, sender, sendResponse) {
switch (message.type) {
case 'getFormatOption':
var response = $('input[name=csvOrEnter_radio]:checked', '#csvOrEnter_form').val();
console.log('formatOption: ' + response);
sendResponse(response);
break;
case 'getFilteringStrategy':
var response = $('input[name=filteringStrategy_radio]:checked', '#filteringStrategy_form').val();
console.log('filteringStrategy: ' + response);
sendResponse(response);
break;
default:
console.error('Unrecognised message: ', message);
}
}
);
The idea that I take some values from radiobuttons from my plugin popup.html.
Manifest:
{
// default for the latest version of Chrome extensions
"manifest_version": 2,
// extension related general info
"name": "FB Interest Search Tool",
"short_name": "FB Interest Search Tool",
"description": "FB Interest Search Tool",
"version": "1.0.0",
"default_locale": "en",
// sets path to popup files
"browser_action": {
"default_icon": "img/128.png",
"default_popup": "popups/popup.html",
"default_title": "FB Interest Search Tool"
},
// sets path to content scripts and when they are injected onto the page
"content_scripts": [
{
"matches": [ "http://*/*", "https://*/*" ],
"css": [ "styles/styles.css" ],
"js": [
"bower_components/jquery.min.js",
"bower_components/jquery.cookie.js"
]
}
],
// sets path to background scripts
"background": {
"scripts": [
"bower_components/jquery.min.js",
"bower_components/jquery.cookie.js",
"bg/background.js",
"content-scripts/rewriteStorage.js"
]
},
"permissions": [
"activeTab",
"http://*/",
"https://*/",
"file:///*/*",
"<all_urls>",
"tabs",
"storage",
"unlimitedStorage",
"storage",
"cookies"
],
"web_accessible_resources": [ "styles/commentblocker_on.css" ]
}
Problem 1: it's called background.js.
I'm not even remotely joking. Well maybe a little.
Since it's included BOTH in the popup and as a background script, there are 2 message listeners registered. And only one can answer:
Note: If multiple pages are listening for onMessage events, only the first to call sendResponse() for a particular event will succeed in sending the response. All other responses to that event will be ignored.
Guess which gets to answer first? My bets are on the background, since it registered the listener first.
While you still see the listener execute in the popup if you try to debug, its sendResponse is ignored because the background already answered.
This one's easy to fix: make a copy, call it popup.js, and keep only relevant logic in both. Don't include the same file in both places unless you're 100% certain code needs to run in both.
Problem 2: Popup is mortal.
When the popup is closed — it's dead, Jim. It simply does not exist: neither the listener, nor the radiobuttons. Therefore, it cannot answer the message.
Fixing this requires reworking the architecture. The only 2 places that can provide storage you can query at any time are:
Background page. It needs to hold the state in a way other than selected element, and the popup needs to inform about the change of state.
chrome.storage API. Both the popup and the content script can read/write to it.
For options, the second one is preferable.

Porting WebExtension from Chrome to Firefox?

I made a working Chrome extension that is not packaged and is just a directory on my computer. I found out that I should be able to port this to Firefox rather easily.
I followed the "Porting a Google Chrome extension" guide on MDN and found that my manifest file is perfect.
I then followed the instructions on how to perform "Temporary Installation in Firefox" of the extension.
However, when I click on any file inside the directory, nothing happens. The extension doesn't load. Any advice? I know the extension works in Chrome fine and loads without error.
manifest.json:
{
"manifest_version": 2,
"name": "ER",
"description": "P",
"version": "1.0",
"browser_action": {
"default_icon": "icon.png",
"default_popup": "popup.html"
},
"background": {
"scripts": [ "background.js" ]
},
"content_scripts": [
{
"matches": [ "SiteIwant" ],
"js": [ "ChromeFormFill.js" ],
"run_at": "document_idle"
}
],
"permissions": [
"*://*/*",
"cookies",
"activeTab",
"tabs",
"https://ajax.googleapis.com/"
],
"externally_connectable": {
"matches": ["SiteIwant"]
}
}
ChromeFormFill.js:
// JavaScript source c
console.log("inside content");
console.log(chrome.runtime.id);
document.getElementById("ID").value = chrome.runtime.id.toString();
Background.js
chrome.runtime.onMessage.addListener(
function (request, sender, sendResponse) {
if (request.data === "info") {
console.log("Recieving Info");
return true;
}
});
chrome.tabs.create(
{
url: 'myUrl'
active: true
}, function (tab) {
chrome.tabs.executeScript(tab.id, { file: 'Run.js', runAt: "document_idle" });
});
Run.js will just alert('hi').
It just won't do anything when I try to load it on Firefox; nothing will happen.
Issues:
In manifest.json:
externally_connectable is not supported:1
Firefox does not support externally_connectable. You can follow bug 1319168 for more information. There is, currently, no expected time when this will be implemented.
You will need to communicate between the code on your site and the WebExtension using a different method. The way to do so is to inject a content script and communicate between the site's code and the content script. The common ways to do this are CustomEvent() or window.postMessage(). My preference is CustomEvent().
Using window.postMessage() is like yelling your message outside and hoping that either nobody else is listening, or that they know that they should ignore the message. Other people's code that is also using window.postMessage() must have been written to ignore your messages. You have to write your code to ignore any potential messages from other code. If either of those were not done, then your code or the other code can malfunction.
Using CustomEvent() is like talking directly to someone in a room. Other people could be listening, but they need to know about the room's existence in order to do so, and specifically choose to be listening to your conversation. Custom events are only received by code that is listening for the event type which you have specified, which could be any valid identifier you choose. This makes it much less likely that interference will happen by mistake. You can also choose to use multiple different event types to mean different things, or just use one event type and have a defined format for your messages that allows discriminating between any possible types of messages you need.
matches value needs to be valid (assumed to be intentionally redacted):
You have two lines (one with a trailing ,, one without; both syntactically correct):
"matches": ["SiteIwant"]
"SiteIwant" needs to be a valid match pattern. I'm assuming that this was changed away from something valid to obfuscate the site that you are working with. I used:
"matches": [ "*://*.mozilla.org/*" ]
In Background.js:
The lines:
url: 'myUrl'
active: true
need to be:
url: 'myUrl',
active: true
[Note the , after 'myUrl'.] In addition, myUrl needs to be a valid URL. I used:
url: 'http://www.mozilla.org/',
A Firefox 48 bug (now long fixed):
Your line:
chrome.tabs.executeScript(tab.id, { file: 'Run.js', runAt: "document_idle" });
In Firefox 48 this line is executed prior to the tab being available. This is a bug. It is fixed in Firefox Developer Edition and Nightly. You will need one of those to test/continue development.
Issues in ChromeFormFill.js:
Another Firefox 48 bug (now long fixed):
chrome.runtime.id is undefined. This is fixed in Developer Edition and Nightly.
Potential content script issue:
I'm going to assume your HTML has an element with an ID = 'ID'. If not, your document.getElementById("ID") will be null. You don't check to see if the returned value is valid.
Running your example code
Once all those errors were resolved, and running under Firefox Nightly, or Developer Edition, it worked fine. However, you didn't have anything that relied on being externally_connectable, which won't function.
agaggi noticed that I had forgotten to include this issue in the original version of my answer.

Chrome extension that acts only when clicked on certain webpages

I'm trying to get my Chrome extension to pop up an alert when the user is on http://google.com/ and clicks on the extension icon.
I have the following manifest:
{
"manifest_version": 2,
"name": "One Megahurt",
"version": "0.1",
"permissions": [
"activeTab"
],
"background": {
"scripts": ["bg.js"],
"persistent": false
},
"browser_action": {
"default_icon": "icon.png"
}
}
and this is bg.js:
chrome.browserAction.onClicked.addListener(function(tab) {
alert('Test!');
})
This code will allow popup an alert on any website, as I don't have any restrictions on which websites this works on. I tried using
if(tab.url === "https://google.com/")
between the first and second lines, but that didn't work.
I'm not sure if I should even be using a background script rather than a content script. I looked in Google's examples and tried using the implementation in "Page action by URL", but that didn't work for me either.
Any help would be appreciated. I should note that I don't really care about the specific issues with the URL--google.com is merely an example. I want to learn to use this for other projects and websites.
EDIT: Adding urls to permissions doesn't restrict which websites the alert pops up on, either.
I ended up using page actions for my solution, per Felix King's suggestion. In retrospect, this was the best solution to use because it doesn't load the extension on every page and cause browser slowdowns (as far as I know).
In addition to adding domains to permissions in the manifest, add a the following code to a background.js.
// When the extension is installed or upgraded ...
chrome.runtime.onInstalled.addListener(function() {
// Replace all rules ...
chrome.declarativeContent.onPageChanged.removeRules(undefined, function() {
// With a new rule ...
chrome.declarativeContent.onPageChanged.addRules([
{
// That fires when a page's URL matches one of the following ...
conditions: [
new chrome.declarativeContent.PageStateMatcher({
pageUrl: { urlMatches: 'http://google.com/' }, // use https if necessary or add another line to match for both
}),
new chrome.declarativeContent.PageStateMatcher({
pageUrl: { urlMatches: 'http://facebook.com/*' },
}) // continue with more urls if needed
],
// And shows the extension's page action.
actions: [ new chrome.declarativeContent.ShowPageAction()]
}
]);
});
});
chrome.pageAction.onClicked.addListener(function(tab) {
chrome.tabs.executeScript(null, { file: "script.js" });
});
Key sections to add in manifest.js are:
"background": {
"scripts": ["res/background.js"],
"persistent": false
}
&
"permissions": [
"declarativeContent", "tabs", "activeTab", "http://google.com", "http://facebook.com/*"
]
I don't have much experience with this, but looking at the example manifests that I've seen, they usually have the a list of domains under permissions. I'm betting that if you used:
"permissions": ["http://www.google.com/", "https://www.google.com/", https://google.com, https://google.com],
it would only run the code on the permissible pages.
Pulled example from:
http://developer.chrome.com/extensions/overview
More detailed info here:
http://developer.chrome.com/extensions/declare_permissions

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