<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title></title>
<script type="text/javascript">
window.onload = function () {
var c = new Calculator('eq');
c.add(2, 3);
};
//if the fouction is a constractor, then the first character "C" should be Upper case.
//Constructor defines properties and inits object.
var Calculator = function (eq) {
this.eqCtrl = document.getElementById(eq);
};
//Prototype defines functions using JSON syntax
Calculator.prototype = {
add: function (x, y) {
var val = x + y;
this.eqCtrl.innerHTML = val;
},
subtract: function (x, y) {
var val = x - y;
this.eqCtrl.innerHTML = val;
}
};
</script>
</head>
<body>
<div id='eq'>
</div>
</body>
</html>
