推荐几种数组去重的方法

<script type="text/javascript">
    var a=["1","2","3","4","5"];
    var b=["7","2","1","8","9"];

    //var newArray=distinct1(a,b);
    var newArray=distinct2(a,b);
    //var newArray=distinct3(a,b);
    console.log(newArray)

    //方式1  for循环（传统写法）
    function distinct1(a,b){
        var arryDiff=[];
        for(var i=0;i<a.length;i++){
            for(var j=0;j<b.length; j++){
                if(a[i]==b[j]){
                    b.splice(j,1);
                }
            }
        }
        arryDiff=a.concat(b);
        return arryDiff;
    }

    //方式2 利用indexof
    function distinct2(a,b){
        var arryDiff=[];
        a.map(item=>{
            if(b.indexOf(item)==-1){
                b.push(item);
                arryDiff=b;
            }
        })

        return arryDiff;
    } 

    //方式3  最简便的
    function distinct3(a,b){
        var arryDiff=[];
        arryDiff=new Set([...a,...b]);
        return arryDiff;
    }
</script>