PersistJS: Cross Browser Client-Side Persistent Storage
Date : 2008 05 22 Category : Tech & Development
AjaxianPaul Duncan announced today the release of PersistJS, a client-side JavaScript persistent storage library.
Currently the only reliable cross-platform and cross-browser mechanism for storing data on the client side are cookies. Unfortunately, using cookies to store persistent data has several problems:
* Size: Cookies are limited to about 4 kilobytes in size.
* Bandwidth: Cookies are sent along with every HTTP transaction.
* Complexity: Cookies are difficult to manipulate correctly.
Modern web browsers have addressed these issues by adding non-Cookie mechanisms for saving client-side persistent data. Each of these solutions are simpler to use than cookies, can store far more data, and are not transmitted along with HTTP requests. Unfortunately, each browser has addressed the problem in a different and incompatible way.
Trying to address the need for client-side storage sans browser-specific techniques or browser plugins, Paul has created an abstraction layer that allows developers to use most of the most common client-side storage mechanisms via a common interface. It currently supports persistent client-side storage through the following backends:
flash: Flash 8 persistent storage. gears: Google Gears-based persistent storage. localstorage: HTML5 draft storage. whatwg_db: HTML5 draft database storage. globalstorage: HTML5 draft storage (old spec). ie: Internet Explorer userdata behaviors. cookie: Cookie-based persistent storage.Other notables features include:
Small (9.3k minified, 3k gzipped) Standalone: Does not need any additional browser plugins orJavaScript libraries to work on the vast majority of current
browsers. Consistent: Provides a consistent, opaque API, regardless of
the browser. Extensible: Custom backends can be added easily. Backwards Compatible: Can fall back to flash or cookies if no
client-side storage solution for the given browser is available. Forwards Compatible: Supports the upcoming versions of Internet
Explorer, Firefox, and Safari (Opera too, if you have Flash). Unobtrusive: Capability testing rather than browser detection, so
newer standards-compliant browsers will automatically be supported.