JavaScript 數組去重方法彙總

時間 2019-11-10

原文原文鏈接

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        <title>JavaScript 數組去重 面試題</title>
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        <script type="text/javascript">
            var arr = [1, 2, 3, 4, 1, 2, 5]; //方法一：ES6 set
            var newArr = [...(new Set(arr))]; console.log(newArr); //方法二：
            function dicArr(arr) { var newArr = []; for(var i = 0, len = arr.length; i < len; i++) { if(newArr.indexOf(arr[i]) == -1) { newArr.push(arr[i]); } } return newArr; } console.log(dicArr(arr)); //方法三
            function dicArr2(arr) { var newArr = [], obj = {}; for(var i = 0, len = arr.length; i < len; i++) { if(!obj[arr[i]]) { obj[arr[i]] = 1; newArr.push(arr[i]); } } return newArr; } console.log(dicArr2(arr)); //方法四
            function dicArr3(arr) { for(var i = 0, len = arr.length; i < len; i++) { for(var j = i + 1; j < len; j++) { if(arr[i] == arr[j]) { arr.splice(j, 1); len--; j--; } } } return arr; } console.log(dicArr3(arr)); //方法五 說明使用map，filter，forEach都行
            function dicArr4(arr) { var newArr = []; // arr.forEach(function(value,key,arr){
                // var flag = arr.indexOf(value,key+1);
                // if(flag == -1){
                // newArr.push(value);
                // }
                // });
                // arr.map(function(value, key, arr) {
                // var flag = arr.indexOf(value, key + 1);
                // if(flag == -1) {
                // newArr.push(value);
                // }
                // });
 arr.filter(function(value, key, arr) { var flag = arr.indexOf(value, key + 1); if(flag == -1) { newArr.push(value); } }); return newArr; } console.log(dicArr4(arr)); </script>
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