I have a webpage that I have to work on all day, it's a portal. I need to reload it about 500 times a day, at least.
I find it to be painfully slow, and I have identified that it makes a network call (just to load a profile picture) to a particular website that I cannot list here, and that network call timesout.
Now because it times out, I don't get a profile picture anyway, but it ends up wasting about 30 seconds per reload.
I can block the domain in the "Networks" tab of Chrome Dev Tools, but I am looking for a more permanent fix. I don't want to have the Dev Tools open all the time since it uses precious screen real estate. I haven't found out a way to permanently block that particular network call which will save me hours per day.
There are 3 things that come to my mind right now:
Block all image assets on the webpage
Initialise the chrome instance using Selenium maybe, and pass in the option to block that network call.
Block that particular website? It hasn't worked for me so far, am I doing it wrong?
I'm comfortable with a fix on any browser (Internet Explorer, Edge, Chrome, Firefox).
Any leads on this one? I can't be the only person to face this, and yet I haven't found out a solution for it without using admin access, which I don't have.
Workaround 1: Call the chrome instance from Selenium, and disable all images. Works, but not the best approach.
from selenium import webdriver
chrome_options = webdriver.ChromeOptions()
prefs = {"profile.managed_default_content_settings.images": 2}
chrome_options.add_experimental_option("prefs", prefs)
driver = webdriver.Chrome(chrome_options=chrome_options)
Workaround 2: Launch Chrome Window from Selenium while executing Network.setBlockedURLs. It will only work in Selenium 4 and above, but it's not working as of now on Selenium 4.0.0.b3.
https://chromedevtools.github.io/devtools-protocol/tot/Network/#method-setBlockedURLs
from selenium import webdriver
driver = webdriver.Chrome()
driver.execute_cdp_cmd('Network.setBlockedURLs', {"urls": ["https://www.somelink.com/*"]})
driver.get("www.mywebsite.com")
As for open an URL upon my extension has been uninstalled, I found the easiest way to do is using chrome.runtime.setUninstallURL, (1) any other good ways?
As for open an URL upon my extension has been first time installed, I don't find something like chrome.runtime.setInstallURL, I implemented the feature with
chrome.runtime.onInstalled.addListener(function(details){
if (details.reason=="install"){chrome.tabs.create({ url: homePage});}
})
I saw AdBlock opens its options page upon first time installed, but it doesn't even used chrome.runtime.onInstalled, its source code is so much complicated , I cannot figure out how it implement the feature ,(2) how it do it ? any other ways to open an URL or its options page upon the extension has been first time installed?
(3) what are the common ways to do something when an extension has been installed or uninstalled?
SetUninstallURL seems to be specifically designed for your task, so it's certainly the right way.
Regarding the installation page, not sure how AdBlock does it, but if you have a persistent background page, one of the simpler ways would be to show the page on every launch if a certain localStorage key is not set.
// background.html startup, for example DOMContentLoaded handler
if ( !localStorage.getItem('intro_shown') ) {
localStorage.setItem('intro_shown', true);
showIntroPage();
}
Local storage of the extension's background page will be persistent, apart from several corner cases (incognito mode in FF, etc).
Upd by Makyen:
chrome.storage seems to be a much better option specifically designed for extension storage needs. It could also be automatically synced with Chrome sync (using chrome.storage.sync)
I'm currently working on a webapp with the polymer-framework.
However, the whole application depends on the geolocation of the device. I'm setting the location in the app-globals file to use it globally, but it takes some time (around 500ms).
My question now is, how can I say to polymer that it should get to work, after the geolocation is set?
Thanks!
I think it depends on the specific behavior you're looking for. A few cases:
Everything still loads when the page loads, including perhaps some app UI and you have a loading icon or similar to indicate that the app is still starting up while you're waiting for the location.
You don't want to show the app until you have the location. Perhaps you don't want the app resources to be loaded at this time either.
You don't even want Polymer to be loaded until you have the location.
There's a lot of options & they may depend on your app architecture a bit, but for a general structure:
show a loader icon on startup & just wait to populate any templates you have until location is set
perhaps keep the hidden attribute on your main app element until location is available &/or don't append the element to the DOM until this point (although with similar resource loading opportunity caveat as in 3 below).
you could wait to add polymer & related elements until location is available, but generally seems silly to do this since your app could be doing this work while the user is waiting for a location to be found.
If you've got a more specific need then more details are probably needed.
I have a "JSFiddle-like" demo of fetching PNG (Binary Blobs) in a tight loop using XHR2. This first demo grabs 341 PNG images, and then saves them in IndexedDB (using PouchDB).
This demo works fine: http://codepen.io/DrYSG/pen/hpqoD
(To operate, first press [Delete DB], Reload Page, wait for Status = Ready (you should see that it plans to fetch 341 tiles), then press [Download tiles]. )
The next demo is the same code (identical JS, CSS, HTML), but it tries to get 6163 PNG files (again from Google Drive). This time you will see many XHR 0 errors in the console log.
http://codepen.io/DrYSG/pen/qCGxi
The Algorithm it uses is as follows:
Test for presence of XHR2, IndexedDB, and Chrome (which does not have binary blobs, but Base64). and show this status info
Fetch a JSON manifest of PNG tiles from GoogleDrive (I have 171 PNG tiles, each 256x256 in size). The manifest lists their names and sizes.
Store the JSON manifest in the DB
MVVM and UI controls are from KendoUI (This time I did not use their superb grid control, since I wanted to explore CSS3 Grid Styling).
I am using the nightly build of PouchDB
All files PNG file are feteched from Google Drive (NASA Blue Marble.
I created the tile pyramid with Safe FME 2013 Desktop.
My guess is what is happening is that all these XHR2 requests are being fired async, being placed on a thread separate from the JavaScript thread, and then when there are too many pending requests, Chrome is getting sick.
FireFox does not have this issue, nor does IE10.
You can fork the code, and try different values for line 10: (max number of tiles to fetch).
I have submitted a bug to Chromium Bugs, but does anyone have any experience in throttling the async XHR2 fetches for large downloads of data to the Chrome Browsers?
The chromium folks acknowledge this is something that they should fix: https://code.google.com/p/chromium/issues/detail?id=244910, but in the meantime I have implemented throttling using jquery defer/resolve to keep the number of threads low.
Update: I am going to delete my codepen, since I don't need to show this error anymore.
I'm writing a web app to be used offline on iOS. I've created a manifest, am serving it up as text/cache-manifest, and it usually works fine, when running inside Safari.
If I add it as an app to my home screen, then turn on Airplane mode, it can't open the app at all -- I get an error and it offers to close the app. (I thought this was the entire purpose of an offline app!)
When I load the app a first time when online, I can see in my logs that it's requesting every page listed in the manifest.
If I turn off Airplane mode, and load the app, I can see the first file it's requesting is my main.html file (which is both listed in the manifest, and has the manifest=... attribute). It then requests the manifest, and all my other files, getting 200's for all (and 304's for anything requested a second time during this load).
When I load the page in Chrome, and click around, the logs show the only thing it's trying to reach on the server is "/favicon.ico" (which is a 404, and which I don't think iOS Safari tries to load, anyway). All of the files listed in the manifest are valid and served without error.
The Chrome inspector lists, under "APPLICATION CACHE", all the cached files I've listed which I expect. The entire set of files is about 50 KB, way under any limit on offline resources that I've found.
Is this supposed to work, i.e., am I supposed to be able to create an offline iOS app using only HTML/CSS/JS? And where do I go about figuring out why it's failing to work offline?
(Related but doesn't sound quite the same to me, since it's about Safari and not a standalone app: "Can't get a web app to work offline on iPod")
I confirm that name 'cache.manifest' solved the offline caching problem in IOS 4.3. Other name simply did not work.
I found debugging HTML5 offline apps to be a pain. I found the code from this article helped me figure out what was wrong with my app:
http://jonathanstark.com/blog/2009/09/27/debugging-html-5-offline-application-cache/
Debugging HTML 5 Offline Application Cache
by Jonathan Stark
If you are looking to provide offline access to your web app, the Offline Application Cache available in HTML5 is killer. However, it’s a giant PITA to debug, especially if you’re still trying to get your head around it.
If you are struggling with the cache manifest, add the following JavaScript to your main HTML page and view the output in the console using Firebug in Firefox or Debug > Show Error Console in Safari.
If you have any questions, PLMK in the comments.
HTH,
j
var cacheStatusValues = [];
cacheStatusValues[0] = 'uncached';
cacheStatusValues[1] = 'idle';
cacheStatusValues[2] = 'checking';
cacheStatusValues[3] = 'downloading';
cacheStatusValues[4] = 'updateready';
cacheStatusValues[5] = 'obsolete';
var cache = window.applicationCache;
cache.addEventListener('cached', logEvent, false);
cache.addEventListener('checking', logEvent, false);
cache.addEventListener('downloading', logEvent, false);
cache.addEventListener('error', logEvent, false);
cache.addEventListener('noupdate', logEvent, false);
cache.addEventListener('obsolete', logEvent, false);
cache.addEventListener('progress', logEvent, false);
cache.addEventListener('updateready', logEvent, false);
function logEvent(e) {
var online, status, type, message;
online = (navigator.onLine) ? 'yes' : 'no';
status = cacheStatusValues[cache.status];
type = e.type;
message = 'online: ' + online;
message+= ', event: ' + type;
message+= ', status: ' + status;
if (type == 'error' && navigator.onLine) {
message+= ' (prolly a syntax error in manifest)';
}
console.log(message);
}
window.applicationCache.addEventListener(
'updateready',
function(){
window.applicationCache.swapCache();
console.log('swap cache has been called');
},
false
);
setInterval(function(){cache.update()}, 10000);
Sometimes an application cache group gets into a bad state in MobileSafari — it downloads every item in the cache and then fires a generic cache error event at the end. An application cache group, as per the spec, is based on the absolute URL of the manifest. I've found that when this error occurs, changing the path to the manifest (eg, cache2.manifest, etc) gives you a fresh cache group and circumvents the problem. I can vouch that all of our web apps work offline in full-screen with 4.2 and 4.3.
No offline web app (as of iOS 4.2) can run without an internet connection (which means Airplane mode, too) when using <meta name="apple-mobile-web-app-capable" content="yes" /> in the html head section. I have verified this with every example I've seen and the ones that use Safari to render the site work fine, but when you throw in that meta tag, it won't work. Try your app without it and you'll see what I mean.
I have found that clearing the Safari cache after enabling Airplane mode to be an effective way of testing whether the app is really functioning offline.
I have sometimes been fooled into thinking that the application cache was working when it wasn't.
I had struggled with this iOS 4.3 "no offline cache" problem since I updated my iPad to 4.3.1 from 4.2. I saw in another post in this site that it was working again in 4.3.2. So I updated by iPad again, now to iOS 4.3.3. But still couldn't get the offline caching to work until I renamed my manifest file to "cache.manifest". Then the caching started working again and I could run my HTML5 offline app from the Home Screen. I did not need to put the favicon.ico in to the cache manifest. And I also had full screen going (setting the "apple-mobile-web-app-capable" to "yes").
I have several working offline and on/offline web apps.
When I turn off airport mode, I get a request for the manifest and some other files.
I don't get requests for images, JavaScript, CSS or cached AJAX files.
If you see requests for your resources, IOS doesn't have them cached.
Safari in general is more picky with manifests.
I suggest you try Safari on your computer.
I have run into the same problem today on iOS 4.3. I was able to fix the problem by adding a favicon.ico file and also adding it to the manifest.
I've written an offline app that still seems to work in 4.2 and 4.2.1; the post is a little dusty, but the code still runs:
http://kentbrewster.com/backchannel/
Remy Sharp has a newer post with code that also works, here:
http://remysharp.com/2011/01/31/simple-offline-application/
His app:
http://rem.im/boggle/
After days of messing with getting offline web apps to work on an iPhone/iPod Touch using the Webserver's HTTP authentication, I discovered these useful nuggets:
Make sure Safari is at the URL root of the web app when tapping "Add to Home Screen". I used jQuery Mobile and was sometimes adding the link with"/#pageId". Caused trouble.
Run your Ajax calls in serial. This might only be important if your web app is using HTTP authentication, but my app was firing a whole slew of Ajax calls on page load in parallel and it caused the app to hang on the "apple-touch-startup-image".
Ajax calls are "successful" when offline (at least using Prototype.js). Test for an actual piece of data in the Ajax response, not just on the HTTP status. I used this to test for displaying cached (SQL) or live data.
In the manifest use "NETWORK:\n*\n". From what I could muster, this is a catch-all statement for anything not explicit in the "CACHE:" section. Use Chrome to make sure your manifest is correct. Look at Chrome's console for errors.
Not directly related, but tripped me up for a bit, openDatabase.transaction() calls are ASYNCHRONOUS! Meaning, the line of JS code after transaction (execute(), error(), success()) will execute BEFORE the success() function.
Good luck!
I found this solution that seemed to work for me, since I also ran into this problem during my development. This fix has worked fine for me so far and also for other people that I've asked to test it with, and I'm able to get it running offline (in airplane mode) and off the home screen after caching and whatnot. I've written a post about it on my site:
http://www.offlinewebapp.com/solved-apple-mobile-web-app-capable-manifest-error/
Delete your current web app icon on the home screen.
Go to settings and clear your Safari browser cache.
Double tap your home button to open the multitasking bar. Find the Safari one, hold your
finger down on it, and exit it.
Please let me know if this works for you also! Good luck!
I've written an app and it works fine through the mobile browser, but when adding the desktop... Doesnt work. I guess apple have given up on IOS4 and all efforts are now on OS5. Shame :(
I have one potential workaround for this - it seems a bit crazy, but here goes... I work with the cache.manifest and full screen apps a lot (here's a test if you need: http://www.mrspeaker.net/2010/07/12/argy-bargy/ - add to home screen then turn on flight mode and it launches - at least, as of iOS 4.2.1)
One weird thing I found is that sometimes it seems that some kind of "meta" information in files can mess them up from being cached - Have you ever noticed that in bash that if you do a "ls" some files (depending on your colour settings) are highlighted for no apparent reason? Files can have meta data that the operating system (I think) adds automagically - and there are ways to remove it... I can't remember why but here's some more details: Strip metadata from files in Snow Leopard
After tearing my hair out one day - and refusing to give up because I knew it SHOULD have worked... Chrome was saying it loaded all the files, but ended with a generic error. In the end I recreated the project structure with blank files and copy/pasted the contents over. It worked - started caching as it was supposed to!
When I looked at the files I noticed there was some meta info. I tried scrubbing this info and the original project worked again. I'm not sure this was the reason it worked again - perhaps it was just a coincidence.
Because it worked, I didn't think too much about it. The same problem happened again some months later and the copy/paste trick worked again. I was busy, so I didn't investigate further - but vowed I would get to the bottom of it the next time it happened.... but I haven't had to yet.
Phew. Anyway, glad I got to write that down somewhere...
[UPDATE: months and months later - I've not been able to reproduce this, so I don't think it's the metadata]