Getting Started With Web Workers

One of the many design goals of the JavaScript language was to keep it single-threaded and, by extension, simple. Though Agraj Mangal must admits that, given the idiosyncrasies of the language constructs, it is anything but simple! But what he means by being “single-threaded” is that there is only one thread of control in JavaScript; yes, sadly, your JavaScript engine can do only one thing at a time. Now, doesn’t that sound too restrictive to make use of multi-core processors lying idle on your machine? HTML5 promises to change all of that.

One school of thought considers JavaScript’s single-threaded nature as a simplification, but the other dismisses it as a limitation. The latter group has a very good point, especially when modern web applications make heavy use of JavaScript for handling UI events, querying or polling server-side APIs, processing large amounts of data, and manipulating the DOM based on the server’s response. Thanks to HTML5 and Web Workers, you can now spawn a new thread–providing true asynchrony. The new worker can run in the background while the main thread processes UI events, even if the worker thread is busy processing a heavy amount of data.