HTML5, JavaScript, and jQuery 24-Hour Trainer

Lesson 30

Web Storage

When the World Wide Web was first envisioned, it was intended as a repository for static documents, primarily academic papers. The key distinguishing feature of the World Wide Web was hyperlinks, which allowed one document to provide a link to another document, and therefore allowed convenient navigation from one piece of information to another.

It wasn't long before web pages started providing more advanced features, such as online shopping. This required web pages to dynamically respond to user interaction. As you have seen, this was facilitated by technologies such as the DOM API, which allows a web page to be modified after it was loaded.

HTML and JavaScript could only take you so far, however. It still was not possible to create web pages or web applications that exhibited the features typically found in native desktop applications. For instance, web pages lacked the following capabilities:

• The ability to interact with the file system beyond the simple file input type.
• The ability to store large amounts of data or configuration information inside the browser (on the client).
• The ability to function without a network connection. Even if a page is cached inside a browser, it typically is not usable without a network connection.
• The ability to perform intensive processing on a background thread without impacting the user experience. Because all JavaScript processing occurs on a single thread, any intensive processing will cause the web page to “lock ...