说明：  Need to learn JavaScript fast? This best-selling reference s visual format and step-by-step, task-based instructions will have you up and running with JavaScript in no time. In this completely updated edition of our best-selling guide to JavaScript, leading Web and computing experts Tom Negrino and Dori Smith use crystal-clear instructions and friendly prose to introduce you to all of today s JavaScript essentials. Along the way, you ll find extensive coverage of Ajax and XML techniques, current browsers (Opera, Safari, Firefox), and more. Visual QuickStart Guide--the quick and easy way to learn! include source code