Chrome manifest V3 extensions and externally_connectable documentation - google-chrome

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.

Related

Can a website detect extensions that are installed using Developed Mode? [duplicate]

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

Loading Aurelia breaks Google API

I have created a reproduction of this bug here (ugly use of Aurelia but to prove the point): https://jberggren.github.io/GoogleAureliaBugReproduce/
If I load Google API and try to list my files in Google Drive my code derived from Googles quickstart works fine. If I use the same code after loading Aurelia I get a script error from gapi stating
Uncaught Error: arrayForEach was called with a non array value
at Object._.Sa (cb=gapi.loaded_0:382)
at Object._.eb (cb=gapi.loaded_0:402)
at MF (cb=gapi.loaded_0:723)
at Object.HF (cb=gapi.loaded_0:722)
at Object.list (cb=gapi.loaded_0:40)
at listFiles (index.js:86)
...
When debugging it seems to be some sort of array check (Chroms says 'native code') that failes after Aurelia is loaded. In my search for an answer I found two other people with the same problem but no solution (Aurelia gitter question, SO Question). Don't know if to report this to the Aurelia team, Google or where the actual problem lays.
Help me SO, you are my only hope.
This is not a perfect solution but works.
aurelia-binding
https://github.com/aurelia/binding/blob/master/src/array-observation.js
Aurelia overrides Array.prototype.* for some reasons.
gapi (especially spreadsheets)
Gapi lib checks to make sure that is it native code or not.
// example
const r = /\[native code\]/
r.test(Array.prototype.push)
conclusion
So, we have to monkey patching.
gapi.load('client:auth2', async () => {
await gapi.client.init({
clientId: CLIENT_ID,
discoveryDocs: ['https://sheets.googleapis.com/$discovery/rest?version=v4'],
scope: 'https://www.googleapis.com/auth/spreadsheets',
});
// monkey patch
const originTest = RegExp.prototype.test;
RegExp.prototype.test = function test(v) {
if (typeof v === 'function' && v.toString().includes('__array_observer__.addChangeRecord')) {
return true;
}
return originTest.apply(this, arguments);
};
});

How do I uninstall a Service Worker?

After deleting /serviceworker.js from my root directory, Chrome still runs the service worker that I removed from my webroot. How do I uninstall the service worker from my website and Chrome so I can log back into my website?
I've tracked the issue down to Service Work's cache mechanism and I just want to remove for now until I have time to debug it. The login script that I'm using redirects to Google's servers for them to login to their Google account. But all I get from the login.php page is an ERR_FAILED message.
Removing Service Workers Programmatically:
You can remove service workers programmatically like this:
navigator.serviceWorker.getRegistrations().then(function(registrations) {
for(let registration of registrations) {
registration.unregister();
}
});
Docs: getRegistrations, unregister
Removing Service Workers Through The User Interface
You can also remove service workers under the Application tab in Chrome Devtools.
You can also go to the URL: chrome://serviceworker-internals/ and unregister a serviceworker from there.
You can do this through Chrome Developer Tool as well as Programatically.
Find all running instance or service worker by typing
chrome://serviceworker-internals/
in a new tab and then select the serviceworker you want to unregister.
Open Developer Tools (F12) and Select Application. Then Either
Select Clear Storage -> Unregister service worker
or
Select Service Workers -> Choose Update on Reload
Programatically
if(window.navigator && navigator.serviceWorker) {
navigator.serviceWorker.getRegistrations()
.then(function(registrations) {
for(let registration of registrations) {
registration.unregister();
}
});
}
In Google Chrome, you can go to Developer tools (F12) -> Application -> Service worker and unregister the service workers from the list for that specific domain.
This method is effective in development mode of a site and mostly they run on localhost which is you may need for other project's development.
FYI, in case you are using MacOS Safari browser, there is one way to forcibly unregister a service worker (steps and images for Safari 12.1):
Safari > Preferences... > Privacy > Manage Website Data…
Enter domain name (ex. 'localhost'), click "Remove"
Note: In addition to service workers, this also will erase all caches, cookies, and databases for this domain.
In addition to the already correct answers given, if you want also to delete the SW cache you can invoke the following method:
if ('caches' in window) {
caches.keys()
.then(function(keyList) {
return Promise.all(keyList.map(function(key) {
return caches.delete(key);
}));
})
}
More in this article (Paragraph: "Unregister a service worker")
Another possibility, via Browser, is by accessing the "Cache Storage" section and click on the "Clear Site Data" button:
You should detecte two API in your devices: getRegistrations and getRegistration. The service-worker not has a unique set of APIs in all platforms. For example, some browsers only have a navigator.serviceWorker.getRegistration, no navigator.serviceWorker.getRegistrations. So you should consider with both.
safely uninstall Service Worker
if ('serviceWorker' in navigator) {
navigator.serviceWorker.getRegistrations().then(function (registrations) {
for (const registration of registrations) {
// unregister service worker
console.log('serviceWorker unregistered');
registration.unregister();
}
});
}
to detect service worker:
navigator.serviceWorker.controller
Code to for deletion of service worker:
navigator.serviceWorker.getRegistrations()
.then(registrations => {
registrations.forEach(registration => {
registration.unregister();
})
});
navigator.serviceWorker.getRegistrations().then(function(registrations) {
for(let registration of registrations) {
registration.unregister()
} })
if(window.navigator && navigator.serviceWorker) {
navigator.serviceWorker.getRegistrations()
.then(function(registrations) {
for(let registration of registrations) {
registration.unregister();
}
});
}
if ('caches' in window) {
caches.keys()
.then(function(keyList) {
return Promise.all(keyList.map(function(key) {
return caches.delete(key);
}));
})
}
if ('serviceWorker' in navigator) {
navigator.serviceWorker.getRegistrations().then(function (registrations) {
for (const registration of registrations) {
// unregister service worker
console.log('serviceWorker unregistered');
registration.unregister();
setTimeout(function(){
console.log('trying redirect do');
window.location.replace(window.location.href); // because without redirecting, first time on page load: still service worker will be available
}, 3000);
}
});
}
IF your service worker don't let you update your files. You will need to replace serviceworker file (sw.js / ServiceWorker.js) with the next code:
self.addEventListener('install', function(e) {
self.skipWaiting();
});
self.addEventListener('activate', function(e) {
self.registration.unregister()
.then(function() {
return self.clients.matchAll();
})
.then(function(clients) {
clients.forEach(client => client.navigate(client.url))
});
});
Source here
as for me , i just use a new nonexistent scope service worker to replace old one,
ServiceWorker: {
events: true,
// what range of URLs a service worker can control. Use a nonexistent path to disable ServiceWorker
scope: '/disable-service-worker/',
},
as for the app.js, i add below code to unregister old sw:
if ('serviceWorker' in navigator) {
navigator.serviceWorker.getRegistrations().then(registrations => {
for (const registration of registrations) {
// keep only serviceWorker which scope is /disable-service-worker/, The purpose is to make serviceWorker useless
if (registration.scope.includes('/disable-service-worker/') === false) {
registration.unregister()
}
}
});
// clear cache of service worker
caches.keys().then(keyList => {
return Promise.all(
keyList.map(key => {
return caches.delete(key);
}),
);
});
}
It can also be done in Chrome through application tab:
This code is compatible with Internet Explorer:
if (navigator.serviceWorker) {
navigator.serviceWorker.getRegistrations().then(
function(registrations) {
for (let idx in registrations) {
registrations[idx].unregister()
}
})
}
IE doesn't support 'for...of' and 'for...of' construction may lead to "'SCRIPT1004: Expected ';'" error
The other answers all add code to the live website to remove the service worker. However I didn't want to leave that live code running forever so I developed a solution that works from within the service worker itself. The steps are below, I posted more detail and explanation on my blog.
Delete the code that registers the service worker.
Replace the service worker script with the following file. The new code must be available from the same URL the previous service worker was at. If you had multiple service worker URLs in the past you should duplicate the code at all of them.
console.log("Cleanup Service Worker Starting");
caches.keys()
.then(keys =>
Promise.all(
keys.map(async key => console.log("caches.delete", key, await caches.delete(key)))))
.then(async () => {
console.log("registration.unregister", await registration.unregister());
})
.then(() => console.log("DONE"))
.catch(console.error);
This code is fairly straight forward. First it deletes all the caches, then it unregisters itself.
Users' browsers will automatically check for an updated service worker the next time they load your website, or the next event 24h after the last service worker check. This means that existing users will run this cleanup on their next visit.
If You want to unregister all of the registered service workers in Browser,
you can do it by opening ex.
Chrome: chrome://serviceworker-internals/
Brave brave://serviceworker-internals/
open DevTools > Console and paste this:
$$('.unregister').forEach(b => b.click())
Open this page: chrome://serviceworker-internals and click to unregister button.
If you want to unregister all service worker open the developer tools and run this code on above page.
document.querySelectorAll("button.unregister").forEach(item=>{ item.click()})
Open in Chrome
chrome://serviceworker-internals/?devtools
then F12 in Console
$$('.unregister').forEach(b => b.click())
Typical JavaScript loop thats compatible with everything:
navigator.serviceWorker.getRegistrations().then(function(registrations) {
var registrationslength = registrations.length;
for (var i = 0; i < registrationslength; i++) {
registrations[i].unregister();
}
})

How can I pass data between two Chrome apps?

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
}
}
);

How to get the root folder in Chrome Extensions?

I am developing a Chrome Extesion for the first time and I am following the only guide that explains something about that: HTML5 ROCKS - FILESYSTEM.
I need to get storage for my extension and I resolved so:
window.webkitStorageInfo.requestQuota(window.PERSISTENT,1024*1024, onInitFs, errorHandler);
Ok, it works.
Now I need to create a xml file into the root, but in "onInitFs" the "fs" var is only a number and "fs.root" can't get it.
function onInitFs(fs){
console.log(fs.root); // -> Undefined
fs.root.getFile('list.xml', {create: true, exclusive: true}, function(fileEntry) {
fileEntry.isFile === true;
fileEntry.name == 'list.xml';
fileEntry.fullPath == '/list.xml';
}, errorHandler);
}
Can anybody explain why it doesn't work and how to resolve this issue?
Using RequestFileSystem within Chrome Extension
In order to use the FileSystem API as a root filesystem for your Chrome extension, you can actually use window.webkitRequestFileSystem instead of requestQuota.
window.webkitRequestFileSystem(window.PERSISTENT, 1024 * 1024, function (filesystem) {
console.log(filesystem);
console.log(filesystem.root);
}, function (e) { console.log("Could not request File System"); });
This does print correctly on Chrome 15,16 and 17 for me:
DOMFileSystem
DirectoryEntry
Using requestQuota for HTML5 apps
Just for reference, this would be the way to actually request the quota (i.e., when not using a Chrome Extension). You have to request the quota (the user sees a little banner at the top of his/her window) first. The RequestFileSystem is called if the user accepts.
window.webkitStorageInfo.requestQuota(PERSISTENT, 1024*1024, function(grantedBytes) {
window.webkitRequestFileSystem(PERSISTENT, grantedBytes, onInitFs, errorHandler);
}, function(e) {
console.log('Error requesting filesystem', e);
});
Eventually it might be necessary to request quota within an extension. Currently this can be circumvented with the unlimitedStorage permission. For the current state of implementation/storage types, see http://code.google.com/chrome/whitepapers/storage.html
Until current stable version 17.x, you cannot use HTML5 FileSystem API in Chrome extension. I have try this, the browser will crash down if I call FileSystem API in background page.
And here is a HTML5 API list what you can use in Chrome extension:
http://code.google.com/chrome/extensions/api_other.html