average for n items in an array

function everage(each) {
	var count = 0;
	var result = [];
	var len = arr.length;
	if (!each) {
		var val = 0;
		for (var i = 0; i < len; i++) {
			val += arr[i];
		}
		return val / len;
	}
	for (var i = 0; i < len; i += each) {
		var val = 0;
		var temparr = arr.slice(i, i + each);
		for (var j = 0; j < temparr.length; j++) {
			val += temparr[j];
		}
		result.push(val / temparr.length);
	}

	return result;
}
var arr = [];
for (var i = 0; i < 100; i++) arr.push(i);
everage();