Peter Lubbers - Pro HTML 5 Programming

216
CHAPTER 9 ■ USING THE HTML5 WEB STORAGE API
Figure 9-1. Checking for browser support
Many browsers do not support sessionStorage for files accessed directly from the file system. Make
sure you serve up the pages from a web server when you run the examples in this chapter. For example,
you can start Python’s simple HTTP server in the code/storage directory as follows:
python -m SimpleHTTPServer 9999
After that, you can access the files at http://localhost:9999/. For example,
http://localhost:9999/browser-test.html.
■ Note As with many APIs, it is possible that a given browser supports only some of the standard. However,
because the Web Storage API is quite small, consistent implementation is already widespread. Consider, also, that
users may choose to turn off Web Storage in their browsers for security reasons even if the browser itself supports
the API.
Setting and Retrieving Values
For now, we’ll focus on the session storage capability as you learn to set and retrieve simple values in a
page. Setting a value can easily be done in a single statement, which we’ll initially write using the longhand
notation:
window.sessionStorage.setItem(‘myFirstKey’, ‘myFirstValue’);