Basic Javascript Callback

Basic Javascript Callback

<!-- This demonstrates a simple javascript callback -->

<div id="now">0</div>
<input type="button" id="goBtn" value="Go" />
<br/>
<div id="result">Let's go!</div>
<script>
var result = document.getElementById('result');
	
function animate(element, callback){
	var left = -1;
	function next(){
		left++;
		if(left < 350){
			element.style.marginLeft = left + 'px';
			element.innerHTML = element.style.marginLeft;
			window.setTimeout(next, 5);
		}
		else{
			callback();
		}
	}
	next();
}

var btn = document.getElementById('goBtn');
btn.onclick = go;

function go(){
	animate(document.getElementById('now'), function(){result.innerHTML = "done! try again?";});
	result.innerHTML = "working...";
}
</script>