javascript prototype 学习

<script type="text/javascript">

Array.prototype.sort = function(){
	if(null == this || undefined == this || 0 >= this.length){
		return;
	}else{
		for(var i = 0; i < this.length; i++){
			var val = this[i];
			var temp;
			for(var j = i; j < this.length; j++){
				if(val > this[j]){
					val = this[j];
					this[j] = this[i];
					this[i] = val;
				}
			}
			this[i] = val;
		}
	}
	return this;
}

var arrays = new Array();
arrays[0] = 5;
arrays[1] = 3;
arrays[2] = 6;
arrays[3] = 2;

document.write(arrays.sort());
</script>