Html5 Localstorage Size Limit for Subdomains

HTML5 localStorage size limit for subdomains

From http://dev.w3.org/html5/webstorage/#disk-space

A mostly arbitrary limit of five megabytes per origin is recommended. Implementation feedback is welcome and will be used to update this suggestion in the future.

It also mentions that :

User agents should guard against sites storing data under the origins
other affiliated sites, e.g. storing up to the limit in
a1.example.com, a2.example.com, a3.example.com, etc, circumventing the
main example.com storage limit.

Is 5MB the de facto limit for W3C Web Storage?

Assuming that the smallest limit for html5 web storage is 5mb, it would be sensible to go with that answer given what information you have presented, and has been presented about W3C web storage. Do beware that everything is in flux, but I don't think this limit will change drastically.

(HTML 5) How much is too much Local Storage?

Check this other Question.
HTML5 localStorage size limit for subdomains

1. It depends on your application.
2. 5 mb is the max size
3. No impact.
4. Database storage is deprecated, so it will not receive more updates. Current browsers support it, yet their implementation may not be standard. So it is not a good idea to use it.

Does HTML5 localStorage maximum size include key names?

Does this include the key names?

Yes those do, they become part of data eg they identify data you store and later retrieve so that got to be saved as well.

How are namespace collisions prevented when using third party JS
scripts?

That's a good question, I generally prefix localStorage with application name. Though a better approach would be to create a hash eg some algorithim that accepts a string like application name, etc and later when reading you use them again.

(How) can I increase the quota limit of LocalStorage in Android WebView

We're talking about HTML5 WebStorageDOCS

There is plenty of question on the same theme, only not Android-specific

• HTML5 localStorage size limit for subdomains
• What is the max size of localStorage values?
• HTML5 LocalStorage size

Fact is, that HTML5 WebStorage suffers from different implementation on different platforms.

Desktop and Mobile Platforms & Browsers combinations differs in size of memory (disk space) quota assigned to each website (domain)

And no, you cannot increase/decrease space allocated for your HTML5 application, there is no such option in WebSettings as Android WebKit Settings Java accessor class, neither in WebKit implementation of HTML5 WebStorage as of now.

citation: http://dev.w3.org/html5/webstorage/#disk-space

A mostly arbitrary limit of five megabytes per origin is recommended. Implementation feedback is welcome and will be used to update this suggestion in the future.

If you really need a large space in your HTML5 Application (no matter if it runs through PhonGap, Titanium, Rhodes or another...), I would strictly recommend you to use HTML Web SQL Database

Even if the DOCS say:

This document was on the W3C Recommendation track but specification work has stopped. The specification reached an impasse: all interested implementors have used the same SQL backend (Sqlite), but we need multiple independent implementations to proceed along a standardisation path.

The Web SQL is now only supported way on Android devices (which you do aim in this question) which allows you to increase/decrease space allocation for your data.

Please note the related question:

• HTML5 IndexedDB, Web SQL Database and browser wars

How can I request an increase to the HTML5 localstorage size on iPad, like the FT web app does?

I happen to know something about this ;)

There's no API for requesting an increase in storage size for an existing database. There is one way to force an increase: write data to the database in such a size that an increase is required, prompting the user. However, this would be slow and there's no way to tell the currently allocated space, so it's not recommended.

Black Frog has part of this correct: the only neat way to do this is to request a very large database when it is opened, for example:

openDatabase('databaseName', '1.0', 'My Database', 50*1024*1024, …

… to request 50MB of space.

However, when the user first visits the site, you may not want to prompt them about a 50MB limit at once; so you might think that you could ask for 5MB at first, and then later re-open it with 50MB? Unfortunately, this doesn't work - the second open attempt, with an increased quantity, succeeds silently, not prompting for a size increase and not actually increasing the available size.

The FT app therefore starts off with a 5MB "preview" database, so that the user isn't prompted on first load. It tries not to exceed this 5MB limit, as any space assigned has to be shared across all databases.

If the user chooses to allow storage of more content, the app then tries to open a database with a different name with 40MB of space (for which the user is prompted to approve 50MB). This allows 40MB in that database, and 5MB in the original preview database, so neither should fail when inserting rows - as 50MB total is currently the limit on iOS.

All browsers currently handle database space limits differently, so if you're planning cross-platform, test carefully. Desktop Safari handles it rather nicely, allowing much larger; Chrome doesn't allow any increase at all; etc. Expect all "HTML5" implementations to differ in strange ways :)

how can i use local storage for storing values of multiple variables?

Here is a good discussion regarding HTML5 Local storage limits
HTML5 localStorage size limit for subdomains

Regarding browsers, here is a list,

Firefox 3.5, Safari 4, IE8, Chrome 4+: HTML5 localStorage; these modern browsers all support the core localStorage functionality defined in the HTML5 draft.

Firefox 2.x and 3.0: Gecko globalStorage, a very early implementation similar to HTML5’s localStorage.

Safari 3.1 & 3.2: HTML5 Database Storage, because Safari 3.1 and 3.2 don’t support HTML5 localStorage.

IE6, IE7: userData persistence, a rarely used IE feature for associating string data with an element on a web page and persisting it between pageviews.

Google Chrome Pre 4: Gears Database API, which is built into earlier versions of Chrome and thus doesn’t require a separate install.

Here is alist of browsers that support this functionality.
https://stackoverflow.com/questions/1194784/which-browsers-support-html5-offline-storage

There is no limit for the number of variables, a detailed explanation for using HTML5 local storage can be found here

Use localStorage across subdomains

This is how I use it across domains...

• Use an iframe from your parent domain - say parent.example
• Then on each child.example domain, just do a postMessage to your parent.example iframe
• All you need to do is setup a protocol of how to interpret your postMessage messages to talk to the parent.example iframe.

How is localStorage space allocated if a user has multiple browsers?

Browsers vendors won't implement shared localStorage. Each browser that supports localStorage will have an independent instance of however it has been implemented.

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