記録配列の消去方法

let arr = [1,2,1,1,1,2,3];
    function unique1(a){
        let temp = [];
        for(let i=0;i

let arr = [1,2,1,1,1,2,3];
   function unique2(arr){
    return Array.prototype.filter.call(arr,function(item,index){
        return arr.indexOf(item) === index;
    });
   }
   console.log(unique2(arr));
   // [1, 2, 3]

let arr = [1,2,1,1,1,2,3];
    function unique3(arr){
        return [...new Set(arr)]
    }
    console.log(unique3(arr));
    // [1, 2, 3]

let arr = [1,2,1,1,1,2,3];
    function unique4(arr){
        return Array.from(new Set(arr))
    }
    console.log(unique4(arr));
 // [1, 2, 3]

let arr = [1,2,1,1,1,2,3];
    function unique5(arr){
        let item = [];
        let obj = {};
        for(let i=0;i