数组去重

三个方式其实效果差不多，只是为了更兼顾不同的环境限制

let arr = [1, 2, true, false, [1, 2], 2, "4", 5, 4, {}, 8, "", "4", 6, false, 6, NaN, 8, 7, [2, 3], 5, 6, "", "6", 4, 8, [1, 2], 3, 1, "8", 4, "6", 9, true, 5, 9, NaN, {}];
function re_1(arr) {
    return Array.from(new Set(arr));
}
function re_2(arr) {
    let arrNew = [];
    for (const iterator of arr) {
        if (!arrNew.includes(iterator)) {
            arrNew.push(iterator);
        }
    }
    return arrNew;
}
function re_3(arr) {
    let arrNew = [];
    for (const iterator of arr) {
        if (iterator !== iterator) {
            let len = arrNew.length;
            let i = 0;
            arrNew.forEach(eleValue => {
                if (!(eleValue !== eleValue)) {
                    i++;
                }
                if (len == i) {
                    arrNew.push(iterator);
                }
            });
        }
        else if (arrNew.indexOf(iterator) === -1) {
            arrNew.push(iterator);
        }
    }
    return arrNew;
}
console.log(re_1(arr).sort());
console.log(re_2(arr).sort());
console.log(re_3(arr).sort());