Chapter 8. Moving and Grooving

In This Chapter

  • Moving an object onscreen

  • Responding to keyboard input

  • Reading mouse input

  • Running code repeatedly

  • Bouncing off the walls

  • Using image-swapping and compound images

  • Reusing code

  • Using external script files

JavaScript has a serious side, but it can be a lot of fun, too. You can easily use JavaScript to make things move, animate, and wiggle. In this chapter, you get to make your pages dance. Even if you aren't interested in animation, you should look over this chapter to find out some important ideas about how to design your pages and your code more efficiently.

Making Things Move

You might think you need Flash or Java to put animation in your pages, but that's not true. You can use JavaScript to create some pretty interesting motion effects. Begin by taking a look at Figure 8-1.


Because this chapter is about animation, most of the pages feature motion. You really must see these pages in your browser to get the effect because a static screen shot can't really do any of these programs justice.

The general structure of this page provides a foundation for other kinds of animation:

  • The HTML is pretty simple. As you'll see when you pop the hood, there really isn't much to the HTML code. It's a couple of divs and some buttons.

    Click the buttons, and the ball moves.

    Figure 8.1. Click the buttons, and the ball moves.

  • The ball is in a special div called sprite. Game developers call the little images ...

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