JavaScript去掉數組中的重複元素

題目：去掉陣列[4,3,"3",3,5,7,5]中的重複元素，回傳[4,3,"3",5,7]

(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);
    }
})();