I added the following code to my otherwise-working Google Chrome Extension…
var storage = chrome.storage ;
console.log("storage is " + storage) ;
var bookmarks = chrome.bookmarks ;
console.log("bookmarks is " + bookmarks) ;
Upon running, the console says
storage is undefined
bookmarks is [object Object]
In other words, bookmarks works OK but storage is missing in action. My manifest has requested both…
{
...
"permissions": [ "bookmarks", "tabs", "storage" ],
}
In case it matters, this extension is installed as an External Extension on Mac OS X. To make sure it was updated correctly, I copied the code above from the files installed into ~/Library/Application Support/Google/Chrome/Default/Extensions. And, of course, I've relaunched Chrome.
Why might chrome.storage be undefined?
Edit: the answer below was written in 2013. Now in 2021, as
Irfan wrote in comment:
chrome.storage is available from content script too. Your extension's
content scripts can directly access user data without the need for a
background page. https://developer.chrome.com/docs/extensions/reference/storage/
Original answer:
LocalStorage is only available in background pages and popup. If you need to acces to some data you will need to pass a message from your current page to a background page. Here is the code :
In your current page:
chrome.extension.sendMessage({action:"getstorage"}, function(response){
console.log("storage is " + response.myVar);
});
In the background page:
chrome.extension.onMessage.addListener(function(request, sender, sendResponse) {
if (request.action == "focusWindow"){
sendResponse({myVar: localStorage.myStorage});
}
});
You can find more examples in the chrome documentation on Message Passing
There is "Reload (Ctrl+R)" link inside extension on "Extensions" tab, clicking on it fixes the problem (I spent few hours). Nor disabling/enabling extension neither restarting Chrome browser will fix the problem. I hope it will save someone's time ;)
Related
I have a google chrome extension that shares some code between it's content script and background process / popup. If it some easy and straightforward way for this code to check if it's executed as content script or not? (message passing behavior differs).
I can include additional "marker" javascript in manifest or call some chrome fnction unavailable from content script and check for exceptions - but these methods looks awkward to be. Maybe it's some easy and clean way to make this check?
To check whether or not your script is running as a content script, check if it is not being executed on a chrome-extension scheme.
if (location.protocol == 'chrome-extension:') {
// Running in the extension's process
// Background-specific code (actually, it could also be a popup/options page)
} else {
// Content script code
}
If you further want to know if you're running in a background page, use chrome.extension.getBackgroundPage()=== window. If it's true, the code is running in the background. If not, you're running in the context of a popup / options page / ...
(If you want to detect if the code is running in the context of an extension, ie not in the context of a regular web page, check if chrome.extension exists.)
Explanation of revised answer
Previously, my answer suggested to check whether background-specific APIs such as chrome.tabs were defined. Since Chrome 27 / Opera 15, this approach comes with an unwanted side-effect: Even if you don't use the method, the following error is logged to the console (at most once per page load per API):
chrome.tabs is not available: You do not have permission to access this API. Ensure that the required permission or manifest property is included in your manifest.json.
This doesn't affect your code (!!chrome.tabs will still be false), but users (developers) may get annoyed, and uninstall your extension.
The function chrome.extension.getBackgroundPage is not defined at all in content scripts, so alone it can be used to detect whether the code is running in a content script:
if (chrome.extension.getBackgroundPage) {
// background page, options page, popup, etc
} else {
// content script
}
There are more robust ways to detect each context separately in a module I wrote
function runningScript() {
// This function will return the currently running script of a Chrome extension
if (location.protocol == 'chrome-extension:') {
if (location.pathname == "/_generated_background_page.html")
return "background";
else
return location.pathname; // Will return "/popup.html" if that is the name of your popup
}
else
return "content";
}
I've been searching for examples and reference and have come up with nothing. I found a note in offscreenTab source code mentioning it cannot be instantiated from a background page (it doesn't have a tab for the offscreenTab to relate to). Elsewhere I found mention that popup also has no tie to a tab.
How do you successfully create an offscreenTab in a Chrome extension?
According to the documentation, offscreenTabs.create won't function in a background page. Although not explicitly mentioned, the API cannot be used in a Content script either. Through a simple test, it seems that the popup has the same limitation as a background page.
The only leftover option is a tab which runs in the context of a Chrome extension. The easiest way to do that is by using the following code in the background/popup:
chrome.tabs.create({url: chrome.extension.getURL('ost.htm'), active:false});
// active:false, so that the window do not jump to the front
ost.htm is a helper page, which creates the tab:
chrome.experimental.offscreenTabs.create({url: '...'}, function(offscreenTab) {
// Do something with offscreenTab.id !
});
To change the URL, use chrome.experimental.offscreenTabs.update.
offscreenTab.id is a tabId, which ought to be used with the chrome.tabs API. However, at least in Chrome 20.0.1130.1, this is not the case. All methods of the tabs API do not recognise the returned tabID.
A work-around is to inject a content script using a manifest file, eg:
{"content_scripts": {"js":["contentscript.js"], "matches":["<all_urls>"]}}
// contentscript.js:
chrome.extension.sendMessage({ .. any request .. }, function(response) {
// Do something with response.
});
Appendum to the background page:
chrome.extension.onMessage.addListener(function(message, sender, sendResponse) {
// Instead of checking for index == -1, you can also see if the ID matches
// the ID of a previously created offscreenTab
if (sender.tab && sender.tab.index === -1) {
// index is negative if the tab is invisible
// ... do something (logic) ...
sendResponse( /* .. some response .. */ );
}
});
With content scripts, you've got full access to a page's DOM. But not to the global object. You'll have to inject scripts (see this answer) if you want to run code in the context of the page.
Another API which might be useful is the chrome.webRequest API. It can be used to modify headers/abort/redirect requests. Note: It cannot be used to read or modify the response.
Currently, the offscreenTabs API is experimental. To play with it, you have to enable the experimental APIs via chrome://flags, and add "permissions":["experimental"] to your manifest file. Once it's not experimental any more, use "permissions":["offscreenTabs"].
I'm trying to close the Options page of the extension.
I have a Cancel button and I'm using this code:
chrome.tabs.getCurrent(null, function(tab) {
chrome.tabs.remove(tab.id, function() {});
});
When I'm trying to use it, it always gives this error:
Uncaught TypeError: Cannot call method 'getCurrent' of undefined
What's wrong with the code?
It works for me with one little fix:
chrome.tabs.getCurrent(function(tab) {
chrome.tabs.remove(tab.id, function() { });
});
Just make sure you're really running this code in options page of your extension and not just some HTML page, because chrome.tabs API is available only for extensions.
Most likely you're running your code from a content script, where chrome.tabs is undefined. If this is the case, you can instead send a message to the background page and have the background page (which has access to chrome.tabs) make the call.
Note that from a background page, you would use chrome.tabs.getSelected since getCurrent will return undefined.
In the options page, you can just do:
window.close()
If you wanted to use chrome.tabs.getCurrent, do you have tabs defined in the permissions section within the manifest?
I have time to continue my extension after a very long time. I checked the documentation again. So it was a inline script, that I had probably blocked with Content Security Policy in the manifest, because I hadn't read the documentation precisely.
Now Chrome blocks inline scripts by default, so I'll have to fix it anyway.
Only this worked for me:
chrome.tabs.query({ active: true }, function(tabs) {
chrome.tabs.remove(tabs[0].id);
});
I'm in the process of making a Google Chrome extension, and encountered a problem.
I'm trying to upload and search through the DOM inside the popup.html.
Here is how I get the current tab (I found the script somewhere, credit doesn't belong to me):
chrome.windows.getCurrent(function(w) {
chrome.tabs.getSelected(w.id,function (response){
)};
My problem is this: I need to traverse through the DOM of the response. When trying to do so manually, I couldn't, as the response variable was now undefined for some reason, so using the Console isn't an option.
When trying to alert the response in the html file, it came as a object. Then, I tried to navigate through the response as if it has been the 'document' object, but no luck either.
Any help will be appreciated greatly.
You can get the selected tab for your popup by passing null as the window id to getSelected. () In your popup you can listen for extension events and execute a script to push the content to your popup:
chrome.extension.onRequest.addListener(
function(request, sender, sendResponse) {
if (request.action == "content")
{
console.log('content is ' + request.content.length + ' bytes');
}
});
chrome.tabs.getSelected(null, function(tab) {
chrome.tabs.executeScript(tab.id, { file: 'scripts/SendContent.js' } );
});
And finally the content script... I have it as "scripts/SendContent.js" in my extension folder, but the script is simple enough you could execute it by putting the code in the code property instead of the name in the file property of the object you pass to executeScript:
console.log('SendContent.js');
chrome.extension.sendRequest( {
action: "content",
host: document.location.hostname,
content: document.body.innerHTML
}, function(response) { }
);
Result:
POPUP: content is 67533 bytes
If you're having trouble, use console.log() and right-click on your page or browser action to inspect it and read your messages on the console (or debug your script from there).
I believe popups are sandboxed the same way that background pages are, so you'll need to use a content script to access the page DOM.
You can inject a content script with chrome.tabs.executeScript, handle your DOM traversal in the content script, then pass back the information you need from the content script to the popup using the message passing API.
I can try to elaborate on this if you give more information about the problem you're trying to solve.
I asked this question before but didn't make it clear that I meant in user script, not in JavaScript from a webpage.So I'll be more clear now.
Is it possible to determine if Google Chrome is in incognito mode via a user-script (basically a script run as an extension in the browser, not a script being run on a webpage)?
To detect whether a window is in
incognito mode, check the incognito
property of the relevant Tab or
Window object. For example:
var bgPage = chrome.extension.getBackgroundPage();
function saveTabData(tab, data) {
if (tab.incognito) {
bgPage[tab.url] = data; // Persist data ONLY in memory
} else {
localStorage[tab.url] = data; // OK to store data
}
http://code.google.com/chrome/extensions/overview.html
If you are developing an Extension then you can use the tabs API to determine if a window/tab incognito.
More information can be found on code.google.com.
If you are just working with a webpage or a userscript, it is not easy, and it is designed to be that way. However, I have noticed that all attempts to open a database (window.database) fail when in incongnito, this is because when in incognito no trace of data is allowed to be left on the users machine.
I haven't tested it but I suspect all calls to localStorage fail too.
Nowadays it's quite easy to do this from a content script. Just use
if(chrome.extension.inIncognitoContext) {
//you're incognito
} else {
//you're not
}