数组去重

一、Set

        let arr = [1, 2, 3, '1', 3, 3, 4, 5, 6];

        let NewArr = [...new Set(arr)];

        // let NewArr = Array.from(new Set(arr));

        console.log(NewArr);

二、迭代，indexOf / includes

        let arr = [1, 2, 3, '1', 3, 3, 4, 5, 6];

        let NewArr = [];
        for (let i = 0; i < arr.length; i++) {
            if (NewArr.indexOf(arr[i]) === -1) {
                NewArr.push(arr[i]);
            };
            // if (!NewArr.includes(arr[i])) {
            //     NewArr.push(arr[i]);
            // };
        };

        console.log(NewArr);

三、排序，再相邻比较

        let arr = [1, 2, 3, '1', 3, 3, 4, 5, 6];

        arr = arr.sort();
        let NewArr = [arr[0]];
        for (var i = 1; i < arr.length; i++) {
            if (arr[i] !== arr[i - 1]) {
                NewArr.push(arr[i]);
            };
        };
        console.log(NewArr);