let arr = [0, 0, 0, 0, 1, 2, 3, 4, 4, 5, 2, 3, 3, 3, 9, 8, 9];
//数组去重法1
console.log(Array.from(new Set(arr)));
//数组去重法2
console.log(...new Set(arr));
    //数组去重法3
    let newarr = [];
    for (var i = 0; i < arr.length; i++) {
        if (newarr.indexOf(arr[i]) == -1) {
            newarr.push(arr[i]);
        };
    };
    console.log(newarr);
    //数组去重法4
    let newarr2 = [];
    arr.sort(); //先将数组排序
    // newarr2.push(arr[0]);
    for (var i = 0; i < arr.length; i++) {
        if (arr[i] !== arr[i + 1]) { //判断后一项 是否跟前一项一样 将后一项放入新数组
            newarr2.push(arr[i]);
        };
    };
    console.log(newarr2);
    //数组去重 法5
    var res = [arr[0]];
    for (var i = 0; i < arr.length; i++) {
        var repeat = false;
        // console.log(res);
        for (var j = 0; j < res.length; j++) {
            if (arr[i] == res[j]) {
                repeat = true;
                break;
            }
        }
        if (!repeat) {
            res.push(arr[i]);
        }
    }
    console.log(res);
    //数组去重 法6 
    var res = [];
    var json = {};
    for (var i = 0; i < arr.length; i++) {
        if (!json[arr[i]]) {
            res.push(arr[i]);
            json[arr[i]] = 1;
        }
    }
    console.log(res);