simple create slide show onlu use pure javascript that was super simple

slide_show.js

var a = 0;
      var b = document.getElementsByClassName("none");
      anim();
      function anim(){
          a++;
          if(a > 3){
              a =1;
          }
          
          b[a].style.display = "block";
          document.getElementById("namaWeb").innerHTML = a;
          setTimeout(anim,2000);
      }

//note for realtime refresh js file use ?$$VERSION$$ on last of src script example src="myjs.js?$$VERSION$$