JavaScript HTML DOM Animation
Learn to create HTML animations using JavaScript.
A Basic Web Page
To demonstrate how to create HTML animations with JavaScript, we will use a simple web page:Example
<!DOCTYPE html>
<html>
<body>
<h1>My First JavaScript Animation</h1>
<div id="animation">My animation will go here</div>
</body>
</html>Create an Animation Container
All animations should be relative to a container element.Example
<div id ="container">
<div id ="animate">My animation will go here</div>
</div> Style the Elements
The container element should be created with style = "position: relative".The animation element should be created with style = "position: absolute".
Example
#container {
width: 400px;
height: 400px;
position: relative;
background: yellow;
}
#animate {
width: 50px;
height: 50px;
position: absolute;
background: red;} Animation Code
JavaScript animations are done by programming gradual changes in an element's style.The changes are called by a timer. When the timer interval is small, the animation looks continuous.
The basic code is:
Example
var id = setInterval(frame, 5);
function frame() {
if (/* test for finished */) {
clearInterval(id);
} else {
/* code to change the element style */
}
} Create the Animation Using JavaScript
Example
function myMove() {
var elem = document.getElementById("animate");
var pos = 0;
var id = setInterval(frame, 5);
function frame() {
if (pos == 350) {
clearInterval(id);
} else {
pos++;
elem.style.top = pos + 'px';
elem.style.left = pos + 'px';
}
}
} 
