According to MDN,
Background scripts are loaded as soon as the extension is loaded and stay loaded until the extension is disabled or uninstalled.
My background script changes its behavior accordingly user’s options, stored on localStorage. When the user change options (using options_ui), localStorage is updated, but since the background script stay loaded, user options are not honored. If the browser is reloaded, options are honored.
How do I reload the background script after the user change options?
As said could be chrome.runtime.reload(), but is better to send a message to the background script and update.
Something like this:
chrome.runtime.onMessage.addListener( function(request, sender)
updateOption(request.option1)
});
in option.js:
chrome.storage.sync.set({'option1': 'new_value'}); ....
chrome.tabs.sendMessage(tab, {option1: 'new_value'});
Kind regards
Related
I am writing a chrome extension, using a content script to inject some javascript code. As follows:
let actualCode = 'My Injected JS Code';
let script = document.createElement('script');
script.textContent = actualCode;
(document.head||document.documentElement).appendChild(script);
For the injected script, I would like to use some value stored in chrome.storage.sync. However, I found that the API is unaccessible to the injected script (storage.sync is undefined). The API is only accessible within the content script, but not for the injected script. Any ideas how I could access chrome.storage API for the injected script too?
PS: I've registered the storage API in manifest.json
PS: When I open the developer's console on chrome and type "chrome.storage", it returns undefined too. I think this might be a permission problem?
The inject way you used for the script, made it work in the web page environment, which doesn't have access to most of Chrome Extensions API.
However, there is an option to use Messages API which allows sending requests from a webpage to the extension by ID.
In this case, you also need to implement a listener in your background page, to answer such requests.
P.S. chrome.storage API also shouldn't be available from page console. You may want to debug it from your background page console or select a content script environment (if the extension has such):
you can use window.postMessage({type : "MESSAGE_NAME"}) in injected script to send "message" event. then use windows.addEventListner("message", callback) in content_script to listen on "message" event.
You can specify the type of message to which you want to listen in the callback function. for instance
in content_script.js
function func_callback(){
if (event.data.type && event.data.type === "MESSAGE_NAME") {
# Your code
}`enter code here`
}
windows.addEventListner("message", func_callback)
in injected_script.js
<button onClick={()=>window.postMessage({type : "MESSAGE_NAME"})}></button>
I have a background script called events.js
I am occassionally getting this error
Unchecked runtime.lastError: Cannot access contents of url
"devtools://devtools/bundled/devtools_app.html?remoteBase=https://chrome-devtools-frontend.appspot.com/serve_file/#ed9d447d30203dc5069e540f05079e493fc1c132/&dockSide=undocked".
Extension manifest must request permission to access this host.
It is apparently being generated not by events.js but by "_generated_background_page.html" but appearing in my background console log.
I suspect it is being caused by my call in events.js to:
chrome.webNavigation.onHistoryStateUpdated.addListener(function(e) {
// do stuff
}
It is driving me nuts. Can anyone please tell me what is going on?
Similar issue happened to me today. One of those facepalm moments. I discovered as i had a breakpoint in my background script to check something before the content-script was executed in the handle message, that this background devtools tab became the active tab and tired to inject the script and not the intended tab from which I activated my extension.
Hence the error.
Cannot access contents of url
"devtools://devtools/bundled/devtools_app.html?remoteBase=https://chrome-devtools-frontend.appspot.com/serve_file/#7345a6d1bfcaff81162a957e9b7d52649fe2ac38/&dockSide=undocked".
chrome.tabs returns undefined despite the fact I set tabs in the permissions block.
"permissions": [
"tabs",
"http://*/*",
"https://*/*"
],
"content_scripts": [
{
"matches": [
"http://*/*",
"https://*/*"
],
"js": [
"js/myScript.js"
],
"all_frames": true
}
],
But in myScript.js the following returns undefined.
chrome.tabs
As content script has its own limitations,
chrome.tabs is only available in background scripts and popup scripts.
If you wanna to use chrome.tabs then pass message from content_script to background script and play with chrome.tabs.
Content scripts have only limited access to Chrome APIs. This access does not include the API you are trying to use (e.g. chrome.tabs). If you need to use that API, you will have to do so in a background script1.
As listed in Chrome's content scripts documentation, the APIs available to a content script are [I have placed deprecated methods in strikethrough format]:
extension ( getURL , inIncognitoContext , lastError , onRequest , sendRequest )
i18n
runtime ( connect , getManifest , getURL , id , onConnect , onMessage , sendMessage )
storage
A couple of the listed APIs are deprecated and have been for some time. Those that are deprecated have moved to different locations (also listed above):
extension.onRequest ➞ runtime.onMessage
extension.sendRequest ➞ runtime.sendMessage
While not officially deprecated, extension.lastError is also available as runtime.lastError. At this point, it is usually referred to at that location:
extension.lastError ➞ runtime.lastError
Partition your extension into background scripts and content scripts
You are going to need to separate your code into what needs to be in a background script and what needs to be in content scripts, based on the capabilities available to each type of script. Content scripts have access to the DOM of the web page into which they are injected, but limited access to extension APIs. Background scripts have full access to the extension APIs, but no access to web page content. You should read the Chrome extension overview, and the pages linked from there, to get a feel for what functionality should be located in which type of script.
It is common to need to communicate between your content scripts and background scripts. To do so you can use message passing. This allows you to communicate information between the two scripts to accomplish things which are not possible using only one type of script.
For instance, in your content script, you may need information which is only available from one of the other Chrome APIs, or you need something to happen which can most appropriately (or only) be done through one of the other Chrome extension APIs. In these cases, you will need to send a message to your background script, using chrome.runtime.sendMessage(), to tell it what needs to be done, while providing enough informaiton for it to be able to do so. Your background script can then return the desired information, if any, to your content script. Alternately, you will have times when the processing will primarily be done in the background script. The background script may inject a content script, or just message an already injected script, to obtain information from a page, or make changes to the web page.
Background script means any script that is in the background context. In addition to actual background scripts, this includes popups and options pages, etc. However, the only page that you can be sure to have consistently available to receive messages from a content script are your actual background scripts defined in manifest.json. Other pages may be available at some times as a result of the user's interaction with the browser, but they are not available consistently.
This answer was moved from a duplicate question, and then modified.
https://developer.chrome.com/extensions/tabs#method-getSelected shows
getSelected
chrome.tabs.getSelected(integer windowId, function
callback)
Deprecated since Chrome 33. Please use tabs.query {active: true}.
Gets the tab that is selected in the specified window.
Maybe, you should use chrome.tabs.query in popup.js like this
chrome.tabs.query({active: true, currentWindow: true}, function(tabs){
console.log(tabs[0].url);
});
, reload your extension and check the result in the inspect element of your extension.
result image
code image
https://developer.chrome.com/extensions/tabs#type-Tab shows that
The URL the tab is displaying. This property is only present if the extension's manifest includes the "tabs" permission.(Just for remind someone forgot. I was forgot it when I just test it.)
Check this answer also https://stackoverflow.com/a/6718277/449345
This one worked for me
chrome.tabs.getSelected(null, function(tab){
console.log(tab);
});
Content Script can be injected programatically or permanently by declaring in Extension manifest file. Programatic injection require host permission, which is generally grant by browser or page action.
In my use case, I want to inject gmail, outlook.com and yahoo mail web site without user action. I can do by declaring all of them manifest, but by doing so require all data access to those account. Some use may want to grant only outlook.com, but not gmail. Programatic injection does not work because I need to know when to inject. Using tabs permission is also require another permission.
Is there any good way to optionally inject web site?
You cannot run code on a site without the appropriate permissions. Fortunately, you can add the host permissions to optional_permissions in the manifest file to declare them optional and still allow the extension to use them.
In response to a user gesture, you can use chrome.permission.request to request additional permissions. This API can only be used in extension pages (background page, popup page, options page, ...). As of Chrome 36.0.1957.0, the required user gesture also carries over from content scripts, so if you want to, you could add a click event listener from a content script and use chrome.runtime.sendMessage to send the request to the background page, which in turn calls chrome.permissions.request.
Optional code execution in tabs
After obtaining the host permissions (optional or mandatory), you have to somehow inject the content script (or CSS style) in the matching pages. There are a few options, in order of my preference:
Use the chrome.declarativeContent.RequestContentScript action to insert a content script in the page. Read the documentation if you want to learn how to use this API.
Use the webNavigation API (e.g. chrome.webNavigation.onCommitted) to detect when the user has navigated to the page, then use chrome.tabs.executeScript to insert the content script in the tab (or chrome.tabs.insertCSS to insert styles).
Use the tabs API (chrome.tabs.onUpdated) to detect that a page might have changed, and insert a content script in the page using chrome.tabs.executeScript.
I strongly recommend option 1, because it was specifically designed for this use case. Note: This API was added in Chrome 38, but only worked with optional permissions since Chrome 39. Despite the "WARNING: This action is still experimental and is not supported on stable builds of Chrome." in the documentation, the API is actually supported on stable. Initially the idea was to wait for a review before publishing the API on stable, but that review never came and so now this API has been working fine for almost two years.
The second and third options are similar. The difference between the two is that using the webNavigation API adds an additional permission warning ("Read your browsing history"). For this warning, you get an API that can efficiently filter the navigations, so the number of chrome.tabs.executeScript calls can be minimized.
If you don't want to put this extra permission warning in your permission dialog, then you could blindly try to inject on every tab. If your extension has the permission, then the injection will succeed. Otherwise, it fails. This doesn't sound very efficient, and it is not... ...on the bright side, this method does not require any additional permissions.
By using either of the latter two methods, your content script must be designed in such a way that it can handle multiple insertions (e.g. with a guard). Inserting in frames is also supported (allFrames:true), but only if your extension is allowed to access the tab's URL (or the frame's URL if frameId is set).
I advise against using declarativeContent APIs because they're deprecated and buggy with CSS, as described by the last comment on https://bugs.chromium.org/p/chromium/issues/detail?id=708115.
Use the new content script registration APIs instead. Here's what you need, in two parts:
Programmatic script injection
There's a new contentScripts.register() API which can programmatically register content scripts and they'll be loaded exactly like content_scripts defined in the manifest:
browser.contentScripts.register({
matches: ['https://your-dynamic-domain.example.com/*'],
js: [{file: 'content.js'}]
});
This API is only available in Firefox but there's a Chrome polyfill you can use. If you're using Manifest v3, there's the native chrome.scripting.registerContentScript which does the same thing but slightly differently.
Acquiring new permissions
By using chrome.permissions.request you can add new domains on which you can inject content scripts. An example would be:
// In a content script or options page
document.querySelector('button').addEventListener('click', () => {
chrome.permissions.request({
origins: ['https://your-dynamic-domain.example.com/*']
}, granted => {
if (granted) {
/* Use contentScripts.register */
}
});
});
And you'll have to add optional_permissions in your manifest.json to allow new origins to be requested:
{
"optional_permissions": [
"*://*/*"
]
}
In Manifest v3 this property was renamed to optional_host_permissions.
I also wrote some tools to further simplify this for you and for the end user, such as
webext-domain-permission-toggle and webext-dynamic-content-scripts. They will automatically register your scripts in the next browser launches and allow the user the remove the new permissions and scripts.
Since the existing answer is now a few years old, optional injection is now much easier and is described here. It says that to inject a new file conditionally, you can use the following code:
// The lines I have commented are in the documentation, but the uncommented
// lines are the important part
//chrome.runtime.onMessage.addListener((message, callback) => {
// if (message == “runContentScript”){
chrome.tabs.executeScript({
file: 'contentScript.js'
});
// }
//});
You will need the Active Tab Permission to do this.
(Cross posted here)
Hi,
I have a sandboxed page (specified in my manifest) which is loaded into an iframe in my extension's background page. From within my sandboxed page, I'd like to open a new window and write to it, i.e.:
var win = window.open(); win.document.write('<p>Hello!</p>');
This works from my extension's background page and from regular web pages, but when invoked from either content scripts or my sandboxed page, the window opens, but I cannot access the win object (it's defined, but empty---console.log outputs "Window {}").
I assume this is due to same-origin policies (with every window being given a uinque-origin within the sandboxed environment). However, since the window opens an about:blank page, I'm confused why this would matter.
Is this a feature? Is there a parameter I can add to my manifest to avoid this? And does anyone know of work-arounds that don't involve using postMessage back to my background page? My ideal solution is to have my sandboxed script open a new window and interact with it directly, not with message passing.
I can provide a full example if necessary, but I'm hoping someone might just know off the top of their head. I'm running Chrome 24.0.1312.57 on Mac and 24.0.1312.68 on Ubuntu if that helps.
Thanks,
Hank
Content scripts, by definition, are part of external regular web pages you load so I'm not really sure how your script could work on a "regular web page" but not the content script. Do you mean the code works when you embed it in your own pages, but not in other pages via the content script?
Regardless, if the script is working properly from your background page, you could always try messaging. (more here: http://developer.chrome.com/extensions/messaging.html)
Script for your sandbox/contentscript:
//send message to background page
chrome.extension.sendMessage({todo: "newWindow"});
In background page:
//create a listener
chrome.extension.onMessage.addListener(
function(request, sender) {
if (request.todo === "newWindow") {
//do your stuff here
var win = window.open(); win.document.write('<p>Hello!</p>');
}
});
Per the cross-post here, the issue is indeed that the opened window is given a unique origin. This was intentional as the members of the standards working group (SWG) felt that it would be more secure to not make an exception for about:blank pages where they inherit the sandbox's origin.
However, to get around this issue, at least for my purposes, I can use the following method. First, forget sandboxing. This workaround uses an iframe embedded in a background page with the src url set to data:text/html,.... This gives a unique origin to the iframe so it's no longer in extension space. That means eval can be used and chrome apis cannot be accessed. Unlike in a sandbox, windows opened from the iframe share that same origin as the iframe, allowing created windows to be accessed. For example:
In a background html page:
<html>
<head>
...
<script src="background.js"></script>
...
</head>
<body>
...
<iframe id="myframe"></iframe>
...
</body>
</html>
In background.js:
...
document.getElementById('myframe').setAttribute('src', 'data:text/html,'+
encodeURI('<html><head>'+
'<script src='+chrome.extension.getURL('jquery.js')+'></script>'+
'<script src='+chrome.extension.getURL('myscript.js')+'></script>'+
...
'</head><body></body></html>'
));
...
In myscript.js
jQuery(document).ready(function(){
...
// To receive messages from background.js.
window.addEventListener('message', function(e){ ... } );
// To send messages to background.js.
parent.postMessage({...}, '*');
// To open AND ACCESS a window.
var win = window.open();
win.document.write('Hello'); // Fails in sandbox, works here.
// Eval code, if you want. Can't do this from an extension
// page loaded normally unless you allow eval in your manifest.
// Here, it's okay!
eval( 'var x = window.open(); x.document.write("Hi!")' );
// No chrome apis.
chrome.log( chrome.extension ); // -> undefined
chrome.log( chrome.windows ); // -> undefined
// No direct access to background page (e.g., parent).
chrome.log( parent ); // -> Window with no properties.
...
});