JS实现数组去重常用的六种方法

双重for循环去重

let arr = [1,2,3,4,3,2,3,5];
let unique = (arr)=>{
    //第一层for循环 数组的前一项
    for(var i=0; i<arr.length; i++){
        //第二层for循环 数组后一项
        for(var j=i+1; j<arr.length; j++){
            if(arr[i] === arr[j]){                
                arr.splice(j,1);//删除反复元素
                j--;//修改下标
            }
        }
    }
    return arr;
}
unique(arr);
console.log(arr);

includes实现数组去重

let arr = [1,3,5,3,5]
let newArr = [];
let unique = (arr)=>{
    let newArr = [];//新数组，用来接管不反复的数组
    for(var i=0; i<arr.length; i++){
        if(! newArr.includes(arr[i])){
            newArr.push(arr[i]);
        }
    }
return newArr;
}
console.log(unique(arr));

indexOf实现数组去重

let arr = [1,3,4,5,3,4,5,32,4];
let newArr = [];
let unique = (arr)=>{
    let newArr = [];//新数组，用来接管不反复的元素
    for(var i=0; i<arr.length; i++){
        if(newArr.indexOf(arr[i])===-1){
            newArr.push(arr[i]);
        }
    }
    rerurn newArr;
}
console.log(unique(arr));

利用set方法去重

let arr = [12,43,23,43,68,12];
let item = [...new Set(arr)];
console.log(item);//[12, 43, 23, 68]

ES6 Array.from()方法

console.log(Array.from(new Set(arr))) ;
console.log([...new Set(arr)]) ;

递归去重

let index = 0
arr = arr.sort()
function loop(index){
  if(index > 1){
    if(arr[index] == arr[index - 1]){
      arr.splice(index,1)
    }
    index--
    loop(index)
  }
}
loop(arr.length - 1)
console.log(arr);