Web Performance Daybook Volume 2

Chapter 2. localStorage Read Performance

Nicholas Zakas

Web Storage (http://dev.w3.org/html5/webstorage/) has quickly become one of the most popular HTML5-related additions to the web developer toolkit. More specifically, localStorage has found a home in the hearts and minds of web developers everywhere, providing very quick and easy client-side data storage that persists across sessions. With a simple key-value interface, we’ve seen sites take advantage of localStorage in unique and interesting ways:

• Disqus (http://www.disqus.com/), the popular feedback management system, uses localStorage to save your comment as you type. So if something horrible happens, you can fire back up the browser and pick up where you left off.

• Google (http://www.google.com/) and Bing (http://www.bing.com/) store JavaScript and CSS in localStorage to improve their mobile site performance (more info: http://www.stevesouders.com/blog/2011/03/28/storager-case-study-bing-google/).

Of the use cases I’ve seen, the Google/Bing approach is one that seems to be gaining in popularity. This is partly due to the difficulties of working with the HTML5 application cache and partly due to the publicity that this technique has gained from the work of Steve Souders and others. Indeed, the more I talk to people about localStorage and how useful it can be for storing UI-related information, the more people I find who have already started to experiment with this technique.

What I find intriguing about this use of localStorage ...