How to use setInterval or setTimeout with a for loop?

Question

I am trying to set an interval when some code runs but only need to do it based on the number of elements there are. Here\'s a quick example:

5 total elements

Ru

Answer 1

let's suppose you're talking about elements of an array or a DOM collection

(function() {
   var arr = [...],
       len = arr.length;


   (function doProcess() {
       if (len--) {
           /* do something with arr[len] */
           setTimeout(doProcess, 20000);
       }
   })();    
})();

Edit: if you cannot reverse the array for any reason just use next version

(function() {
   var arr = [...],
       len = arr.length;


   (function doProcess(i) {
       if (i) {
            console.log(len - i);
           /* do something with arr[len - i] */
           setTimeout(function() { doProcess(--i); }, 20000);
       }
   })(len);    
})();