<script>
    var i=1;
    var arr=[];
    while (i<100000){
        arr.push(String(i));
        i+=1;
    }

    var time1=(new Date()).getTime();
    console.log(arr.indexOf("999"));
    var time2=(new Date()).getTime();
    console.log(time2-time1);

    var time3=(new Date()).getTime();
    console.log(arr.join("|").indexOf("999"));
    var time4=(new Date()).getTime();
    console.log(time4-time3);

</script>