数组去重

    const arr = [1,2,1,2,3,4,1,5,1,2,6]
    //方法一
    const arr1 = [...new Set(arr)]
    //方法二
    const arr2 = Array.from(new Set(arr))
    //方法三
    function noDup1(arr){
        let res = []
        for(var i=0;i<arr.length;i++){
            if(!res.includes(arr[i])){
                res.push(arr[i])
            }
        }
        return res
    }
    //方法四
    function noDup2(arr){
        arr = arr.sort()
        let i = 0 
        while(i<arr.length-1){
            if(arr[i]===arr[i+1]){
                arr.splice(i,1)
            }else{
                i++
            }
        }
        return arr
    }