js数组去重

一、利用ES6 Set去重（ES6中最常用）

let arr = [1,2,1,3]
arr = [...new Set(arr)] // [1,2,3]

二、利用for嵌套for，然后splice去重（ES5中最常用）

let arr = [1, 3, 2, 4, 5, 3, 2, 1, 4, 6, 7, 7, 6, 6]
function deWeight(arr){            
        for(var i=0; i<arr.length; i++){
            for(var j=i+1; j<arr.length; j++){
                if(arr[i]==arr[j]){         //第一个等同于第二个，splice方法删除第二个
                    arr.splice(j,1);
                    j--;
                }
            }
        }
return arr;
}

三、利用indexOf去重

let arr = [1, 3, 2, 4, 5, 3, 2, 1, 4, 6, 7, 7, 6, 6]
let arr1 = []
for(var i=0;i<arr.length;i++){
    if(arr1.indexOf(arr[i]) === -1){
        arr1.push(arr[i])
    }
}
return arr1

四、利用sort()

let arr = [1, 3, 2, 4, 5, 3, 2, 1, 4, 6, 7, 7, 6, 6]
let arr1 = []
arr = arr.sort()
for(var i=0;i<arr.length;i++){
    if(arr[i] !== arr[i-1]){
        arr1.push(arr[i])
    }
}
return arr1

五、利用includes

let arr = [1, 3, 2, 4, 5, 3, 2, 1, 4, 6, 7, 7, 6, 6]
let arr1 = []
arr = arr.sort()
for(var i=0;i<arr.length;i++){
    if(!arr1.includes(arr[i])){//includes 检测数组是否有某个值
        arr1.push(arr[i])
    }
}
return arr1

六、利用filter

let arr = [1, 3, 2, 4, 5, 3, 2, 1, 4, 6, 7, 7, 6, 6]
arr.filter((item,index,arr)=>{
    return arr.indexof(item,0) === index
})