JSFiddle - React, Tailwind, and code Playground

JavaScript

var x = [1, 2, 3, 4]

var count = 0;
var output = [];

function square(array) {
  var value = array[count];
  console.log('above', value, count, array);

  if (value) {
    y = value * value;
    output.push(y);
    count++;
    square(array)
  }
  console.log('below', value, count, array)
  return output

}
console.log(square(x));