使用Array.prototype为数组添加一个去重的方法

要求输入一个数组：

var arr = [false, true, undefined, null, NaN, 0, 1, {}, {}, 'a', 'a', NaN]

输出：
[false, true, undefined, null, NaN, 0, 1, {}, {}, 'a']

注意：NaN === NaN 为false，{} === {}为false

Array.prototype.uniq = function () {
        if (!this.length || this.length == 0) return this;
                var res = [], key, hasNaN = false, temp = {};
        for (var i = 0 ; i < this.length; i++) {
                        if (typeof this[i] === 'object') {
                                res.push(this[i]);
            } else if (this[i] != this[i]) { // 如果当前遍历元素是NaN
                if (!hasNaN) {
                    res.push(this[i]);
                    hasNaN = true;
                }
            } else {
                key = typeof(this[i]) + this[i];
                if (!temp[key]) {
                    res.push(this[i]);
                    temp[key] = true;
                }
            }
        }
        return res;
}   
var arr = [false, true, undefined, null, NaN, 0, 1, {}, {}, 'a', 'a', NaN]
console.log(arr.uniq())  //[false, true, undefined, null, NaN, 0, 1,{}, {}, "a"]

方法优化：

Array.prototype.uniq = function () {
    var res = [];
    var flag = true;
    this.forEach(function(x) {
        if (res.indexOf(x) == -1) {
            if (x != x) {
                if (flag) {
                    res.push(x);
                    flag = false;
                }
            } else {
                res.push(x);
            }
        }
    })
    return res;
}
var arr = [false, true, undefined, null, NaN, 0, 1, {}, {}, 'a', 'a', NaN]
console.log(arr.uniq())  //[false, true, undefined, null, NaN, 0, 1,{}, {}, "a"]