LOCAL STORAGE

ersistent local storage is one of the areas where native client applications have held an advantage over web applications. For native applications, the operating system typically provides an abstraction layer for storing and retrieving application-specific data like preferences or runtime state.

What we really want is

a lot of storage space on the client that persists beyond a page refresh and isn’t transmitted to the server

INTRODUCING HTML5 STORAGE

What I will refer to as “HTML5 Storage” is a specification named Web Storage, which was at one time part of the HTML5 specification proper, but was split out into its own specification for uninteresting political reasons.

USING HTML5 STORAGE HTML5 Storage is based on named key/value pairs. You store data based on a named key, then you can retrieve that data with the same key. The named key is a strin

USING HTML5 STORAGE

With web storage, web applications can store data locally within the user’s browser.

Before HTML5, application data had to be stored in cookies, included in every server request. Web storage is more secure, and large amounts of data can be stored locally, without affecting website performance.

Unlike cookies, the storage limit is far larger (at least 5MB) and information is never transferred to the server.

Web storage is per origin (per domain and protocol). All pages, from one origin, can store and access the same data.

LIMITATIONS IN CURRENT BROWSERS limitations of the now-standardized HTML5 Storage. I’ll give you the answers first, then explain them. The answers, in order of importance, are “5 megabytes,” “QUOTA_EXCEEDED_ERR,” and “no.”

“5 megabytes” is how much storage space each origin gets by default. This is surprisingly consistent across browsers, although it is phrased as no more than a suggestion in the HTML5 Storage specification.

BEYOND NAMED KEY-VALUE PAIRS: COMPETING VISIONS

hile the past is littered with hacks and workarounds, the present condition of HTML5 Storage is surprisingly rosy. A new API has been standardized and implemented across all major browsers, platforms, and devices. As a web developer, that’s just not something you see every day, is it? But there is more to life than “5 megabytes of named key/value pairs,” and the future of persistent local storage is… how shall I put it… well, there are competing visions.

BEYOND NAMED KEY-VALUE PAIRS: COMPETING VISIONS

While the past is littered with hacks and workarounds, the present condition of HTML5 Storage is surprisingly rosy. A new API has been standardized and implemented across all major browsers, platforms, and devices. As a web developer, that’s just not something you see every day, is it? But there is more to life than “5 megabytes of named key/value pairs,” and the future of persistent local storage is… how shall I put it… well, there are competing visio