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/*
Examples From
JavaScript: The Definitive Guide, Fourth Edition
Legal matters: these files were created by David Flanagan, and are
Copyright (c) 2001 by David Flanagan. You may use, study, modify, and
distribute them for any purpose. Please note that these examples are
provided "as-is" and come with no warranty of any kind.
David Flanagan
*/
<html>
<!-- This is the dynamic element we will animate. We wrap the h1 tag in a -->
<!-- div because IE 4 won't move the h1 without a div or a span container. -->
<div id="title" style="position:absolute"><h1>Hello</h1></div>
<!-- This is the JavaScript code that performs the animation -->
<script>
// These variables set the parameters for our animation
var id = "title"; // Name of the element to animate
var numFrames = 30; // How many frames to display
var interval = 100; // How long to display each frame
var x0 = 100, y0 = 100; // The element's starting position
var x1 = 500, y1 = 500; // The element's ending position
var dx = (x1 - x0)/(numFrames-1); // Distance to move horizontally each frame
var dy = (y1 - y0)/(numFrames-1); // Distance to move vertically each frame
var frameNum = 0; // Frame we are at now
var element = null; // The element to be animated
// First, we find the element to be animated. Use a DOM-compliant technique
// if the browser supports it, otherwise fall back on browser-specific code.
if (document.getElementById) { // If this is a DOM-compliant browser
element = document.getElementById(id); // Use the DOM method
}
else if (document.all) { // Otherwise, if the IE API is supported
element = document.all[id]; // Use the all[] array to find the element
}
else if (document.layers) { // Else if the Netscape API is supported
element = document.layers[id]; // Use the layers[] array to get the element
}
// If we found the element to animate using one of the techniques above,
// start animating it by calling nextFrame() every interval milliseconds.
if (element) {
var intervalId = setInterval("nextFrame()", interval);
}
// This function is called repeatedly to display each frame of the animation.
// It moves the element using either the DOM API for setting CSS style
// properties, or, if the browser does not support that API, it uses
// the Netscape Layer API.
function nextFrame() {
if (element.style) {
// If the browser supports it, move the element by setting CSS
// style properties. Note the inclusion of the units string.
element.style.left = x0 + dx*frameNum + "px";
element.style.top = y0 + dy*frameNum + "px";
}
else {
// Otherwise, assume that element is a Layer, and move it by
// setting its properties. We could also use element.moveTo().
element.left = x0 + dx*frameNum;
element.top = y0 + dy*frameNum;
}
// Increment the frame number, and stop if we've reached the end.
if (++frameNum >= numFrames) clearInterval(intervalId);
}
</script>
</html>
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