Insert 1 to N items into a JavaScript Array. The original array gets modified and is also returned to enable chaining

[Array].insertAt.js

//inserts 1 to n items into an array arr starting at position pos
function insertAt(arr, pos /* , item1, item2, ...itemN */){
  switch (arguments.length){
		case 0:	case 1:	case 2:
			break;
		case 3:
			//the default case would work here also, but it's faster it we avoid the extra concat and slice...
			arr.splice(pos, 0, item);
			break;
		default:
			var args = [pos, 0].concat([].slice.call(arguments, 2));
			arr.splice.apply(arr, args); 
			break;
	}
	//to enable chaining
  return arr;
}

I got confused and created this same script previously as Anonymous.

replaced Array.prototype.slice with [].slice

Hi Xose: 'arguments[2]' instead of 'item' fixes a little typo at line 8 ;)