js método de deduplicación de matriz simple

1. Utilice empalme

var arr = [1, 2, 123, 124, 12, 1, 3, 2, 4]

        function QC(arr) {
    
    
            for (var i = 0; i < arr.length; i++) {
    
    
                for (var j = i + 1; j < arr.length; j++) {
    
    
                    if (arr[i] === arr[j]) {
    
    
                        arr.splice(j, 1);// 删除从下标j开始的1个数
                        j--;
                    }
                }
            }
            return arr
        }
        console.log(QC(arr));

2. Utilice indexOf

 function QC(arr) {
    
    
            var newArr = []
            for (var i = 0; i < arr.length; i++) {
    
    
                if (newArr.indexOf(arr[i]) === -1) {
    
    //新数组中不存在则返回-1
                    newArr.push(arr[i])
                }
            }
            return newArr
        }
        console.log(QC(arr));

3. Utilice ordenar

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

El uso incluye

        function QC(arr) {
    
    
            var newArr = []
            for (var i = 0; i < arr.length; i++) {
    
    
                if (!newArr.includes(arr[i])) {
    
    
                    newArr.push(arr[i])
                }
            }
            return newArr
        }
        console.log(QC(arr));