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DOM Animations

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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 Full Animation Using JavaScript #

Example #

var id = null; function myMove() { var elem = document.getElementById("animate"); var pos = 0; clearInterval(id); id = setInterval(frame, 5); function frame() { if (pos == 350) { clearInterval(id); } else { pos++; elem.style.top = pos + 'px'; elem.style.left = pos + 'px'; } } }

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