14-3.txt

Javascript语言开发经典教程开发

<!-- The image that will be animated. Give it a name for convenience. -->
<IMG SRC="images/0.gif" NAME=animation>

<SCRIPT>
// Create a bunch of off-screen images, and get them started 
// loading the images we're going to animate.
var images = new Array(10);
for(var i = 0; i < 10; i++) {
    images[i] = new Image();                 // Create an Image object.
    images[i].src = "images/" + i + ".gif";  // Tell it what URL to load.
}

// Later, when we want to perform our animation, we can use these URLs,
// knowing that they've been loaded into the cache. Note that we perform
// the animation by assigning the URL, not the Image object itself.
// Also note that we call the image by name, rather than as document.images[0].
function animate()
{
    document.animation.src = images[frame].src;
    frame = (frame + 1)%10;
    timeout_id = setTimeout("animate()", 250);  // Display next frame later.
}
var frame = 0;         // Keep track of what frame of the animation we're on.
var timeout_id = null; // This allows us to stop the animation.
</SCRIPT>

<FORM>                   <!-- Buttons to control the animation. -->
  <INPUT TYPE=button VALUE="Start" 
	 onClick="if (timeout_id == null) animate()">
  <INPUT TYPE=button VALUE="Stop" 
	 onClick="if (timeout_id) clearTimeout(timeout_id); timeout_id=null;">
</FORM>