After preparing the migration of my chrome manifest V2 extension to manifest V3 and reading about the problems with persistent service workers I prepared myself for a battle with the unknown. My V2 background script uses a whole bunch of globally declared variables and I expected I need to refactor that.
But to my great surprise my extension background script seems to work out of the box without any trouble in manifest V3. My extension uses externally_connectable. The typical use case for my extension is that the user can navigate to my website 'bla.com' and from there it can send jobs to the extension background script.
My manifest says:
"externally_connectable": {
"matches": [
"*://localhost/*",
"https://*.bla.com/*"
]
}
My background script listens to external messages and connects:
chrome.runtime.onMessageExternal.addListener( (message, sender, sendResponse) => {
log('received external message', message);
});
chrome.runtime.onConnectExternal.addListener(function(port) {
messageExternalPort = port;
if (messageExternalPort && typeof messageExternalPort.onDisconnect === 'function') {
messageExternalPort.onDisconnect(function () {
messageExternalPort = null;
})
}
});
From bla.com I send messages to the extension as follows
chrome.runtime.sendMessage(EXTENSION_ID, { type: "collect" });
From bla.com I receive messages from the extension as follows
const setUpExtensionListener = () => {
// Connect to chrome extension
this.port = chrome.runtime.connect(EXTENSION_ID, { name: 'query' });
// Add listener
this.port.onMessage.addListener(handleExtensionMessage);
}
I tested all scenarios including the anticipation of the famous service worker unload after 5 minutes or 30 seconds inactivity, but it all seems to work. Good for me, but something is itchy. I cannot find any documentation that explains precisely under which circumstances the service worker is unloaded. I do not understand why things seem to work out of the box in my situation and why so many others experience problems. Can anybody explain or refer to proper documentation. Thanks in advance.
I am in the process of building a Chrome extension, and for the whole thing to work the way I would like it to, I need an external JavaScript script to be able to detect if a user has my extension installed.
For example: A user installs my plugin, then goes to a website with my script on it. The website detects that my extension is installed and updates the page accordingly.
Is this possible?
Chrome now has the ability to send messages from the website to the extension.
So in the extension background.js (content.js will not work) add something like:
chrome.runtime.onMessageExternal.addListener(
function(request, sender, sendResponse) {
if (request) {
if (request.message) {
if (request.message == "version") {
sendResponse({version: 1.0});
}
}
}
return true;
});
This will then let you make a call from the website:
var hasExtension = false;
chrome.runtime.sendMessage(extensionId, { message: "version" },
function (reply) {
if (reply) {
if (reply.version) {
if (reply.version >= requiredVersion) {
hasExtension = true;
}
}
}
else {
hasExtension = false;
}
});
You can then check the hasExtension variable. The only drawback is the call is asynchronous, so you have to work around that somehow.
Edit:
As mentioned below, you'll need to add an entry to the manifest.json listing the domains that can message your addon. Eg:
"externally_connectable": {
"matches": ["*://localhost/*", "*://your.domain.com/*"]
},
2021 Update:
chrome.runtime.sendMessage will throw the following exception in console if the extension isn't installed or it's disabled.
Unchecked runtime.lastError: Could not establish connection. Receiving end does not exist
To fix this, add this validation inside the sendMessage callback
if (chrome.runtime.lastError) {
// handle error
}
I am sure there is a direct way (calling functions on your extension directly, or by using the JS classes for extensions), but an indirect method (until something better comes along):
Have your Chrome extension look for a specific DIV or other element on your page, with a very specific ID.
For example:
<div id="ExtensionCheck_JamesEggersAwesomeExtension"></div>
Do a getElementById and set the innerHTML to the version number of your extension or something. You can then read the contents of that client-side.
Again though, you should use a direct method if there is one available.
EDIT: Direct method found!!
Use the connection methods found here: https://developer.chrome.com/extensions/extension#global-events
Untested, but you should be able to do...
var myPort=chrome.extension.connect('yourextensionid_qwerqweroijwefoijwef', some_object_to_send_on_connect);
Another method is to expose a web-accessible resource, though this will allow any website to test if your extension is installed.
Suppose your extension's ID is aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, and you add a file (say, a transparent pixel image) as test.png in your extension's files.
Then, you expose this file to the web pages with web_accessible_resources manifest key:
"web_accessible_resources": [
"test.png"
],
In your web page, you can try to load this file by its full URL (in an <img> tag, via XHR, or in any other way):
chrome-extension://aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa/test.png
If the file loads, then the extension is installed. If there's an error while loading this file, then the extension is not installed.
// Code from https://groups.google.com/a/chromium.org/d/msg/chromium-extensions/8ArcsWMBaM4/2GKwVOZm1qMJ
function detectExtension(extensionId, callback) {
var img;
img = new Image();
img.src = "chrome-extension://" + extensionId + "/test.png";
img.onload = function() {
callback(true);
};
img.onerror = function() {
callback(false);
};
}
Of note: if there is an error while loading this file, said network stack error will appear in the console with no possibility to silence it. When Chromecast used this method, it caused quite a bit of controversy because of this; with the eventual very ugly solution of simply blacklisting very specific errors from Dev Tools altogether by the Chrome team.
Important note: this method will not work in Firefox WebExtensions. Web-accessible resources inherently expose the extension to fingerprinting, since the URL is predictable by knowing the ID. Firefox decided to close that hole by assigning an instance-specific random URL to web accessible resources:
The files will then be available using a URL like:
moz-extension://<random-UUID>/<path/to/resource>
This UUID is randomly generated for every browser instance and is not your extension's ID. This prevents websites from fingerprinting the extensions a user has installed.
However, while the extension can use runtime.getURL() to obtain this address, you can't hard-code it in your website.
I thought I would share my research on this.
I needed to be able to detect if a specific extension was installed for some file:/// links to work.
I came across this article here
This explained a method of getting the manifest.json of an extension.
I adjusted the code a bit and came up with:
function Ext_Detect_NotInstalled(ExtName, ExtID) {
console.log(ExtName + ' Not Installed');
if (divAnnounce.innerHTML != '')
divAnnounce.innerHTML = divAnnounce.innerHTML + "<BR>"
divAnnounce.innerHTML = divAnnounce.innerHTML + 'Page needs ' + ExtName + ' Extension -- to intall the LocalLinks extension click here';
}
function Ext_Detect_Installed(ExtName, ExtID) {
console.log(ExtName + ' Installed');
}
var Ext_Detect = function (ExtName, ExtID) {
var s = document.createElement('script');
s.onload = function () { Ext_Detect_Installed(ExtName, ExtID); };
s.onerror = function () { Ext_Detect_NotInstalled(ExtName, ExtID); };
s.src = 'chrome-extension://' + ExtID + '/manifest.json';
document.body.appendChild(s);
}
var is_chrome = navigator.userAgent.toLowerCase().indexOf('chrome') > -1;
if (is_chrome == true) {
window.onload = function () { Ext_Detect('LocalLinks', 'jllpkdkcdjndhggodimiphkghogcpida'); };
}
With this you should be able to use Ext_Detect(ExtensionName,ExtensionID) to detect the installation of any number of extensions.
Another possible solution if you own the website is to use inline installation.
if (chrome.app.isInstalled) {
// extension is installed.
}
I know this an old question but this way was introduced in Chrome 15 and so I thought Id list it for anyone only now looking for an answer.
Here is an other modern approach:
const checkExtension = (id, src, callback) => {
let e = new Image()
e.src = 'chrome-extension://'+ id +'/'+ src
e.onload = () => callback(1), e.onerror = () => callback(0)
}
// "src" must be included to "web_accessible_resources" in manifest.json
checkExtension('gighmmpiobklfepjocnamgkkbiglidom', 'icons/icon24.png', (ok) => {
console.log('AdBlock: %s', ok ? 'installed' : 'not installed')
})
checkExtension('bhlhnicpbhignbdhedgjhgdocnmhomnp', 'images/checkmark-icon.png', (ok) => {
console.log('ColorZilla: %s', ok ? 'installed' : 'not installed')
})
I used the cookie method:
In my manifest.js file I included a content script that only runs on my site:
"content_scripts": [
{
"matches": [
"*://*.mysite.co/*"
],
"js": ["js/mysite.js"],
"run_at": "document_idle"
}
],
in my js/mysite.js I have one line:
document.cookie = "extension_downloaded=True";
and in my index.html page I look for that cookie.
if (document.cookie.indexOf('extension_downloaded') != -1){
document.getElementById('install-btn').style.display = 'none';
}
You could have the extension set a cookie and have your websites JavaScript check if that cookie is present and update accordingly. This and probably most other methods mentioned here could of course be cirvumvented by the user, unless you try and have the extension create custom cookies depending on timestamps etc, and have your application analyze them server side to see if it really is a user with the extension or someone pretending to have it by modifying his cookies.
There's another method shown at this Google Groups post. In short, you could try detecting whether the extension icon loads successfully. This may be helpful if the extension you're checking for isn't your own.
Webpage interacts with extension through background script.
manifest.json:
"background": {
"scripts": ["background.js"],
"persistent": true
},
"externally_connectable": {
"matches": ["*://(domain.ext)/*"]
},
background.js:
chrome.runtime.onMessageExternal.addListener(function(msg, sender, sendResponse) {
if ((msg.action == "id") && (msg.value == id))
{
sendResponse({id : id});
}
});
page.html:
<script>
var id = "some_ext_id";
chrome.runtime.sendMessage(id, {action: "id", value : id}, function(response) {
if(response && (response.id == id)) //extension installed
{
console.log(response);
}
else //extension not installed
{
console.log("Please consider installig extension");
}
});
</script>
Your extension could interact with the website (e.g. changing variables) and your website could detect this.
But there should be a better way to do this. I wonder how Google is doing it on their extension gallery (already installed applications are marked).
Edit:
The gallery use the chrome.management.get function. Example:
chrome.management.get("mblbciejcodpealifnhfjbdlkedplodp", function(a){console.log(a);});
But you can only access the method from pages with the right permissions.
A lot of the answers here so far are Chrome only or incur an HTTP overhead penalty. The solution that we are using is a little different:
1. Add a new object to the manifest content_scripts list like so:
{
"matches": ["https://www.yoursite.com/*"],
"js": [
"install_notifier.js"
],
"run_at": "document_idle"
}
This will allow the code in install_notifier.js to run on that site (if you didn't already have permissions there).
2. Send a message to every site in the manifest key above.
Add something like this to install_notifier.js (note that this is using a closure to keep the variables from being global, but that's not strictly necessary):
// Dispatch a message to every URL that's in the manifest to say that the extension is
// installed. This allows webpages to take action based on the presence of the
// extension and its version. This is only allowed for a small whitelist of
// domains defined in the manifest.
(function () {
let currentVersion = chrome.runtime.getManifest().version;
window.postMessage({
sender: "my-extension",
message_name: "version",
message: currentVersion
}, "*");
})();
Your message could say anything, but it's useful to send the version so you know what you're dealing with. Then...
3. On your website, listen for that message.
Add this to your website somewhere:
window.addEventListener("message", function (event) {
if (event.source == window &&
event.data.sender &&
event.data.sender === "my-extension" &&
event.data.message_name &&
event.data.message_name === "version") {
console.log("Got the message");
}
});
This works in Firefox and Chrome, and doesn't incur HTTP overhead or manipulate the page.
You could also use a cross-browser method what I have used.
Uses the concept of adding a div.
in your content script (whenever the script loads, it should do this)
if ((window.location.href).includes('*myurl/urlregex*')) {
$('html').addClass('ifextension');
}
in your website you assert something like,
if (!($('html').hasClass('ifextension')){}
And throw appropriate message.
If you have control over the Chrome extension, you can try what I did:
// Inside Chrome extension
var div = document.createElement('div');
div.setAttribute('id', 'myapp-extension-installed-div');
document.getElementsByTagName('body')[0].appendChild(div);
And then:
// On web page that needs to detect extension
if ($('#myapp-extension-installed-div').length) {
}
It feels a little hacky, but I couldn't get the other methods to work, and I worry about Chrome changing its API here. It's doubtful this method will stop working any time soon.
If you're trying to detect any extension from any website,
This post helped: https://ide.hey.network/post/5c3b6c7aa7af38479accc0c7
Basically, the solution would be to simply try to get a specific file (manifest.json or an image) from the extension by specifying its path. Here's what I used. Definitely working:
const imgExists = function(_f, _cb) {
const __i = new Image();
__i.onload = function() {
if (typeof _cb === 'function') {
_cb(true);
}
}
__i.onerror = function() {
if (typeof _cb === 'function') {
_cb(false);
}
}
__i.src = _f;
__i = null;
});
try {
imgExists("chrome-extension://${CHROME_XT_ID}/xt_content/assets/logo.png", function(_test) {
console.log(_test ? 'chrome extension installed !' : 'chrome extension not installed..');
ifrm.xt_chrome = _test;
// use that information
});
} catch (e) {
console.log('ERROR', e)
}
Here is how you can detect a specific Extension installed and show a warning message.
First you need to open the manifest file of the extension by going to chrome-extension://extension_id_here_hkdppipefbchgpohn/manifest.json and look for any file name within "web_accessible_resources" section.
<div class="chromewarning" style="display:none">
<script type="text/javascript">
$.get("chrome-extension://extension_id_here_hkdppipefbchgpohn/filename_found_in_ web_accessible_resources.png").done(function () {
$(".chromewarning").show();
}).fail(function () {
// alert("failed.");
});
</script>
<p>We have detected a browser extension that conflicts with learning modules in this course.</p>
</div>
Chrome Extension Manifest v3:
const isFirefox = chrome.runtime.OnInstalledReason.CHROME_UPDATE != "chrome_update";
For FireFox, I believe chrome.runtime.OnInstalledReason.BROWSER_UPDATE will be "browser_update": https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime/OnInstalledReason
In background.js, I create a popup like so:
chrome.windows.create({
focused: true,
width: 1170,
url : "settings/index.html",
type: "popup"
}, function(popup) {
tab_app = popup.id;
alert(tab_app);
});
I store the id in tab_app.
how can I pass a value from background.js to my popup?
I'm trying like that:
chrome.tabs.executeScript(tab_app, {code: "alert("+message.add+");"});
but it keeps telling me that this tab id doesnt exist.. im assuming its because its a popup. will appreciate some help.
Since it's your extension page, the method of choice is Messaging.
Note: you can't use the per-tab messaging of chrome.tabs.sendMessage, since this explicitly targets the content script context (that doesn't exist for extension pages). You need to use the "broadcast" chrome.runtime.sendMessage that will send to all other extension pages.
If you can have more than one popup-type window at a time, this may be a problem - you need some identifier to go along. You could pass it as a URL parameter or a URL hash, e.g. "settings/index.html?id=foo" or "settings/index.html#foo". If you don't expect more than one popup-type window (you can always check if one is open before opening a new one), it doesn't matter.
If you really need dynamic code loading or execution, not just passing data (doubtful), you need to be mindful of CSP.
You can dynamically load a script from your extension's package by just creating and adding a <script> tag to the document.
However, you can't, by default, pass a string of code and eval it in the extension context. You could add 'unsafe-eval' to CSP string, but that's a bad idea in general.
Most probably, you only need some commands to be passed along with data. Pure messaging is great for it, just look at the docs.
This old answer of mine may be of use - I'm using opening a new tab and passing data there to print it.
You cannot call executeScript in the your extension pages. If you try to use executeScript in your extension page. It will show error :
Unchecked runtime.lastError while running tabs.executeScript: Cannot
access contents of url
"chrome-extension://extension_id/yourPage.html".
Extension manifest must request permission to access this host
Now you cannot add "chrome-extension://<extension_id>/yourPage.html" under permissions in manifest.json because it is invalid and not allowed.
Instead you can use message passing.
background.js:
function createNewtab(){
var targetId = null;
chrome.tabs.onUpdated.addListener(function listener(tabId, changedProps) {
if (tabId != targetId || changedProps.status != "complete")
return;
chrome.tabs.onUpdated.removeListener(listener);
chrome.tabs.sendMessage(targetId, {message : "loadNewTab"},function(response){
// do nothing yet
});
});
chrome.windows.create({
focused: true,
width: 1170,
url : chrome.extension.getURL("settings/index.html"),
type: "popup"
}, function(popup) {
targetId = popup.tabs[0].id;
});
}
index.js:
chrome.runtime.onMessage.addListener(function(request, sender, sendResponse){
switch (request.message){
case "loadNewTab":
alert("HI")
break;
}
});
I have created two Chrome apps and I want to pass some data (string format) from one Chrome app to another Chrome app. Appreciate if someone can help me with showing the correct way of doing this?
It's an RTFM question.
From Messaging documentation (note that it mentions extensions, but it works for apps):
In addition to sending messages between different components in your extension, you can use the messaging API to communicate with other extensions. This lets you expose a public API that other extensions can take advantage of.
You need to send messages using chrome.runtime.sendMessage (using app ID) and receive them using chrome.runtime.onMessageExternal event. If required, long-lived connections can also be established.
// App 1
var app2id = "abcdefghijklmnoabcdefhijklmnoab2";
chrome.runtime.onMessageExternal.addListener(
// This should fire even if the app is not running, as long as it is
// included in the event page (background script)
function(request, sender, sendResponse) {
if(sender.id == app2id && request.data) {
// Use data passed
// Pass an answer with sendResponse() if needed
}
}
);
// App 2
var app1id = "abcdefghijklmnoabcdefhijklmnoab1";
chrome.runtime.sendMessage(app1id, {data: /* some data */},
function(response) {
if(response) {
// Installed and responded
} else {
// Could not connect; not installed
// Maybe inspect chrome.runtime.lastError
}
}
);
I'm just trying out the file system API.
As described in http://www.html5rocks.com/en/tutorials/file/filesystem
code:
window.webkitStorageInfo.requestQuota(PERSISTENT, 1024 * 1024, function (grantedBytes) {
window.requestFileSystem(PERSISTENT, grantedBytes, successCallback, errorHandler);
}, function (e) {
console.log('Error', e);
});
function successCallback(fs) {
window.fileSystem = fs;
fs.root.getFile('kiki.txt', {
create: false,
exclusive: true
},
function (fileEntry) {
// Create a FileWriter object for our FileEntry (log.txt).
fileEntry.createWriter(function (fileWriter) {
fileWriter.onwriteend = function (e) {
console.log('Write completed.');
};
fileWriter.onerror = function (e) {
console.log('Write failed: ' + e.toString());
};
fileWriter.seek(fileWriter.length);
// Create a new Blob and write it to log.txt.
var blob = new Blob(['Lorem Ipsum'], {
type: 'text/plain'
});
fileWriter.write(blob);
}, errorHandler);
}, errorHandler);
}
(the create: false is because I already created that file before).
Chrome asks permission to use the file system and I grant it.
When I try to read it, I can, it's persistent. But where is it saved?
According to the docs, it is saved in the root folder ("/"), but it is not there (I'm using nginx). I search the entire HD for this file ("kiki.txt") and it is not found.
So where is it saved?
You are using the HTML5 file system APIs but trying to find data files on the server.
Client browsers will save the data most probably on the client's file system. Quote from the link you provided: http://www.html5rocks.com/en/tutorials/file/filesystem/
With the FileSystem API, a web app can create, read, navigate, and write to a sandboxed section of the user's local file system.
As for your question - each browser will have their own implementation of the HTML5 file system APIs and the data might be saved anywhere using custom format.
As a key value pair in a database stored in the user profile which may be different for each person based on operating system, browser, and configuration.
But here is one example, copied from:Where is the html5 local database located on a client machine?
C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\Profiles\<profile-name>\webappsstore.sqlite