JavaScript remove duplicate elements from array

(function() { 'use strict'; function filter1(arr) { var b = []; arr.forEach(function(i) { if (b.indexOf(i) == -1) { b.push(i); } }); return b; } function filter2(arr) { var b = {}, c = []; arr.forEach(function(i) { b[i] = b[i] ? b[i] : {}; var type = typeof i; if (!b[i][type]) { b[i][type] = true; c.push(i); } }); return c; } function timer(fn, arr) { console.time('filter'); fn.call(this, arr); console.timeEnd('filter'); } function testArr(n) { // var arr = [4,3,"3",3,5,7,5]; var arr = []; for (var i = 0; i < n; i++) { arr.push(i); arr.push(i + ""); } return arr; } for (var i = 1; i <= 100; i++) { console.log(i * 10); var arr = testArr(i * 10); timer(filter1, arr); timer(filter2, arr); } })();