Filtering an array using Javascript 1.6 or jQuery

arrayFilter.js

var arr = [0, 1, 2, 3, null, undefined, '', "test"];

/* Remove 'falsy' values */
//using the filter method available in Javascript 1.6
var output = arr.filter(function(x){return !!x});
console.log(output)// [1, 2, 3, "test"]

//using jQuery grep function
var jqOutput = $.grep(arr, function(x){return !!x});
console.log(jqOutput )// [1, 2, 3, "test"]

/* Get numbers */
//filter
var numOutput = arr.filter(function(x){return typeof x === "number"});
console.log(numOutput )// [0, 1, 2, 3]

//jQuery grep
var jqNumOutput = $.grep(arr, function(x){return typeof x === "number"});
console.log(jqNumOutput )// [0, 1, 2, 3]