Look at the for loop Javascript code example

Example 1: javascript for loop

var colors=["red","blue","green"];
for (let i = 0; i < colors.length; i++) { 
  console.log(colors[i]);
}

Example 2: for in range javascript

function* range(start=0, end=null, step=1) {
  if (end == null) {
    end = start;
    start = 0;
  }

  for (let i=start; i < end; i+=step) {
    yield i;
  }
}