字符串-数组-常用算法-去重

方法一:

  var arr = [1,1,2,5,5,8,3,8,3];
    var result = [];
    for(var i = 0;i < arr.length;i++){
            var value = arr[i];
            if(result.indexOf(value) == -1){//在数组result中找元素是value的索引值,没找到返回值为-1,把该元素添加到result里
                result.push(value);
            }
        }
    console.log(result);

结果 : [1, 2, 5, 8, 3]

方法二:不但可以去重,还会进行排序

 var arr = [1,2,8,5,3,5,2,7,9,6,3,6,3,5,3,5];
    var result = {};
    for(var i = 0;i < arr.length;i++){
            var value = arr[i];
            result[value] = 1;
        }
    console.log(Object.keys(result));

结果: ["1", "2", "3", "5", "6", "7", "8", "9"]
方法三：ES6新出的set方法，代码超级简短

    var arr = [1,2,4,5,3,2,2];//需要去重的数组

    var set = new Set(arr); //{1，2，4，5，3}
    var newArr= Array.from(set); //再把set转化为array
    console.log(newArr,set); //[1，2，4，5，3]