The method of packaging an array deduplication

One,

        function noRepeat(arr) {
            var arr1 = [];
            for (var i = 0; i < arr.length; i++) {
                var item = arr[i];
                var flag = true;
                for (var j = 0; j < arr1.length; j++) {
                    if (arr1[j] === item) {
                        flag = false;
                        break;
                    }
                }
                if (flag) arr1.push(item);
            }
            return arr1;
        }
        console.log(noRepeat(arr));

two,

        function noRepeat(arr) {
            for (var i = 0; i < arr.length; i++) {
                var item = arr[i];
                for (var j = i + 1; j < arr.length; j++) {
                    if (item === arr[j]) {
                        delete arr[j];
                    }
                }
            }
            var arr1 = [];
            for (var prop in arr) {
                arr1.push(arr[prop]);
            }
            return arr1;
        }
        console.log(noRepeat(arr));

three,

        function noRepeat(arr) {
            var arr1 = [];
            for (var i = 0; i < arr.length; i++) {
                var item = arr[i];
                if (arr1.indexOf(item) === -1) arr1.push(item);
            }
            return arr1;
        }
        console.log(noRepeat(arr));