Array iteration problem

add1.js

/*

	Solution to the Array Iteration Problem @ http://blog.jazzychad.net/2012/08/01/array-iteration-problem.html
	
	---
	
	add1 - increments items in an array matching specified value
	
	param: arr - array of integers to manipulate
	param: val - integer, value to increment
	param: n   - integer, control value specifying behavior of manipulation
	
	n == 0 means increment all occurrences of val
	
	n > 0  means increment up to n occurrences of val
	       from left-to-right (forward)
	
	n < 0  means increment up to n occurrences of val
	       from right-to-left (backward)
	
	return: arr with proper values incremented
	
*/

var add1 = function(arr, val, n){
	for(var ii = n >= 0 ? 0 : arr.length - 1, jj = n >= 0 ? arr.length : 0, count = 0; ii != jj && (count < Math.abs(n) || n == 0); ii += n >= 0 ? 1 : -1){
		if(arr[ii] == val){
			arr[ii]++;
			count++;
		}
	}
	return arr;
}

var arr = [1, 4, 1, 5, 1];
add1(arr, 1, 2);
console.log(arr);