[Javascript] Plus one with string number over integer size

gistfile1.js

/**
 * How TO Use :
 * var sExample = "1";
 * var sResult = sPlusOne(sExample.split("")); // result : 2
 * Why :
 * When you want to add one to a number over Integer. ex) adding menu in order.
 */

var sPlusOne = function( aInputArray ){
	var aArray = $.merge([], aInputArray);
	var iLength = aArray.length;
	if( aArray[iLength-1] == 9 ){
		aArray[iLength-1] = 0;
		if( iLength == 1 ){
			aArray.unshift(1);
		}else{
			var i = 2;
			while( i <= iLength ){
				if( aArray[iLength-i] != 9){
					aArray[iLength-i] = parseInt(aArray[iLength-i])+1;
					break;
				}else{
					aArray[iLength-i] = 0;
				}
				if( i == iLength ){
					aArray.unshift(1);
				}
				i++;
			}
		}
	}else{
		aArray[iLength-1] = parseInt(aArray[iLength-1])+1;
	}
	return aArray.join('');
};