Recursive Array Sum in Javascript

array_sum.js

function arraySum(arr) {
	if(typeof arr == 'number') return arr;
	return arr.filter(function(item) {
		return Array.isArray(item) || Number.isFinite(item);
	}).reduce(function(memo, item) {
		return memo + arraySum(item);
	}, 0);
}
var arr = [7,4,1, [3,true,2], 1, '123'];
alert(arraySum(arr));