Pass an array and a value, get back the closest number.

closestNumber

var getClosestNum = function(num, ar) {
  	var i = 0, closestDiff, currentDiff;
		if(ar.length) {
		closest = ar[0];
		for(i;i<ar.length;i++) {
			closestDiff = Math.abs(num - closest);
			currentDiff = Math.abs(num - ar[i]);
			if(currentDiff < closestDiff) {
				closest = ar[i];
			}
			closestDiff = null;
			currentDiff = null;
	}
		//returns first element that is closest to number
		return closest;
	}
		//no length
		return false;
};