How to make a timeout with the assignment of classes in turn in an array of elements?

Question

JavaScript

An array of three elements. Initially, all elements is-hidden
must be assigned a class in turn with the delay is-activeand loop it forever.
How to write a loop that iterates over this array? Why doesn't it work?

for(i = 0; i < this.elements.length; i++) {
      setTimeout(function() {
        this.elements[i].active = !this.elements[i].active
        this.elements[i].hidden = !this.elements[i].hidden
      }, 2500)
    }

https://codepen.io/kodej/pen/GMXxxR

Answer 1

So ?