I have an HTML5/jquery mobile web app at http://app.bluedot.mobi. It is used for long distance races to track competitors via SPOT satellite tracking. The issue I have not yet resolved is that when loading the app when no data connection exists, the browser throws a "no data connection" alert popup as it is attempting to fetch the manifest during the checking event. Even when a data connection is present, loading the app can take a very long time. There are ~ 500 files to check. The fastest way to load the app (from a phone) is to be in airplane mode and dismiss the browser's alert - not so elegant.
Rather than force an update on users who tend to be in the backcountry with a spotty connection, I want to use applicationCache.update() programmatically, giving the user control over the process and speeding up app load whether on or offline.
Is this currently possible with the HTML5 spec and respective browser implementations?
Sounds like you need the abort() method. Unfortunately it is very new, and it will probably be a while before it is implemented by the majority of mobile browsers.
There are ~ 500 files to check.
It sounds like you're implying that the browser checks each file to see if there's any of them which has changed. This is not correct. The browser only checks the manifest file if that has changed, and that is a simple byte check. If the manifest file has not changed, the browser believes nothing has changed.
So if your application is slow to start, it might be your because your application is complex and there's alot of HTML and Javascript to parse. I would advise you to take a look at the application and see if there's anything you can optimize. In that case, you might want to take a look at Yahoo's Best Practices for Speeding Up Your Web Site page.
For example, I noticed you have a lot of Javascript code in the HEAD section. The beforementioned article advices us to move all Javascript (To the extent of what's possible) to the bottom of the page, so that the browser can start rendering the page as soon as possible. And there's a lot of other sound advice in the article. So take a look, I'm sure you'll find it useful. :-)
Related
I currently have a swing Application with a WebView panel(via some javafx in swing). The WebPanel interfaces with the application itself by using 'invalid' protocols, keywords and hooks, and basically is not distinguishable from the rest of the UI.
All of that information is relevant, because on intial load, the webpage has to load, which can take a bit of time depending on server and client side variables.
What I need to do is have a way to save an offline copy of the webpage, and display it immediately on load. Since this is more critical and will not follow the rules of the actual underlying cache, I think it would be better if I manually did this instead.
Any information to help out here would be appreciated, like the best way to go about saving an offline copy of a website. I am hoping their is an easy way to achieve this without scanning the html for other references, recursing into all of these references, and reassigning the address to a local one, which seem a bit much for what I am trying to achieve.
The reason for the web based ui is because this portion of the UI is regularly updated, and gives the greatest freedom without pushing unnecessary program updates.
When deploying a Polymer app to production, what's the recommended way to avoid requests for Polymer's source map files? The files platform.js.map and polymer.js.map weigh in at ~800K. Even if those downloads are deferred, surely there is some user impact (e.g., on mobile devices) simply spending bandwidth getting those files, isn't there?
Currently, my deployment process simply skips over the .map files, but when looking at the production site, I still see the browser trying to find them. Those requests fail with a 404, since the files aren't deployed. In theory the 404s shouldn't slow anything down, but it's still distracting to see 404s show up. It makes it look like there's a problem when in fact there isn't.
I could write a Grunt task to strip off the //# sourceMappingURL line from the associated .js files, but I was wondering if anyone has experimented with other means by which to drop the source maps. Or have people found that there is literally no impact on user experience when including those files?
I would consider it a browser bug if any browser loaded source maps when the user isn't using debug tools on the site in question. Are you noticing a significant number of requests to your source maps in your logs?
If you're using Google Chrome Devtools and want the source maps to be ignored, you can go to settings and uncheck the corresponding "Enable Javascript source maps" check box.
I'm developing a mobile web app, and I'd like to take advantage of the new HMTL5 caching features. The app consists in a photo manager: the user can create albums, store photos, edit pictures and data, and so on. I use the jQuery Mobile framework and all data is stored client-side (webstorage) apart from images, which are uploaded to the server.
I have not added the HTML5 caching yet, but I rely on the normal browser caching for images, and when the user edits an image and this is uploaded to the server, I change the querystring attached to the image request so I get the updated version (a trick I came to know here on stackoverflow).
I'd like to use HTML5 caching for everything, except for images, since this trick works like a charm, but I understand that once I add HMTL5 caching, every resource is:
either cached and not updated until a new manifest is detected / I do it programmatically (and I can't choose which resource to update) (CACHE section)
or not cached at all and reloaded everytime (NETWORK section)
Is there a way to have the cake and eat it too? :-)
Thank you very much.
Not every resource is cached once you start caching, depends on what is specified in your manifest file, so you could try to take out from the manifest the image urls you do not want to get cached.
With HTML5's offline capabilities is it possible to create an app that will persist after the connection is lost and the browser is closed? Specifically, here's what I'd like to do:
Connect to the app while online. Download the entire app including a small database it runs on.
Close the browser and disconnect.
Open the browser again while offline and load the app from the local cache.
Thanks to Mark Pilgrim's excellent book I believe I have an idea of how to accomplish the first step, I'm mainly wondering if the last step is possible. If this is possible, I'm guessing it requires some configuration of the browser. Any settings I should be aware of that aren't obvious?
Thanks very much for any help offered.
The last step should be possible - it just depends on what extent you want to implement it to. To my knowledge it shouldn't require any browser settings. You just have to be aware of the limitations of local storage, which I believe is 5mb max at the moment (for most browsers). Obviously you'd have to perform the checks for such permissions as outlined int the Dive Into Html5 guide you linked.
The quickest and dirtiest way is to simply issue a GET request to your online app. If it responds correctly, then use the online version. If not, use the local cache. Just disguise the timeout/failed response as a 'loading' screen.
How do I setup the basic switching of offline storage modes (offline/online) in Web SQL? I know there's javascript
window.navigator.onLine. I can check the mode and then go through a process...
//All GET/POST performed with AJAX
//On Startup pulldown entire accessible database into offline storage (Doesn't seem secure IMO)
//if(read) pull from offline
//if(create, update, delete and online) pull from standard db, mark changes with offline expiration flag
//if(create, update, delete and offline) perform operation on offline storage, persist with POST when next online (change flag)
I'm asking if there is any OOB integration for these standard tasks?
The navigator.online property generally isn't very useful - in a desktop browser all it does is hook into the File -> Work Offline menu. It may be more useful on an iPad, I don't know because I don't have one, and I'm guessing there's not a File menu, but I would recommend you test.
A common approach to this issue is to set up two easily distinguishable files in the fallback section of your manifest. Every time you want to connect back to the server attempt to fetch the file with AJAX and, in the callback, check it to see if you got the online file or the fallback, then branch accordingly.
You shouldn't be using Web SQL as that spec was nixed a new months ago. You should be using Localstorage. Unless you are specifically coding for something like the iphone, but even then you dont know how long the spec will be in webkit.