How to implement array deduplication and duplicate element statistics in ES6

The content of this article is about how to implement array deduplication and repeated element statistics in ES6. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

1. Deduplication

This uses the feature of ES6 Set structure that does not allow data duplication

let arr1 = [1,1,2,3,1,2,4,2];
//先将数组转化为Set数据类型，然后再转回数组类型
let dedupeArr = Array.from(new Set(arr1));

2. Statistics

let count = 0;
let obj = {}; //最终返回的数据
dedupeArr.forEach(i=>{
    count = 0;
    arr1.forEach(j=>{
        if(i===j) count++;
    })
    obj[i] = count;//键名为i(数组元素)，值为count(出现次数)
})

3. Traverse objects

for(let i = 0 in obj){
    console.log(i+':'+obj[i]);
}
// 数组元素:出现次数
// 1:3
// 2:3
// 3:1
// 4:1

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