<html>
<head><title>Testing</title></head>
<body bgcolor=white>
<script>
function Listener(initial) {
this.i=initial;
this.process = function process() {
var user = document.forms[0].amount.value - 0;
this.i += user;
document.getElementById("rctmpx").innerHTML = "Your current balance is: " + this.i;
}
}
</script>
<span id="rctmpx">Welcome. Balance is: 0</span> <p>
<form>
Enter value here: <input type="text" name="amount">
</form> <p>
<input type="button" value="Push me!" onClick="a.process()"> to advance the balance by the value you entered above.
<script>
a = new Listener(0);
</script>
</body>
</html>