Looping range, step by step?

Question

I am trying to define a function range which takes 3 integer parameters: start, end, and step.

The function should return an array of numbers from start to end count

Answer 1

Your for loop isn't doing anything. In particular, it's not creating an array. You're just trying to return the 3 inputs, not the array of numbers that's supposed to be generated. But since you're combining them with the comma operator, you just return the last parameter (see What does a comma do in JavaScript expressions?).

Your loop needs a body that adds the current element to an array.

const range = function(start, end, step) {
  const result = []
  for (let i = start; i <= end; i += step) {
    result.push(i);
  }
  return result;
}

console.log(range(0, 10, 2));

Answer 2

Create an array and use your existing for loop to push the values to that array andthen return the array. I have given both a for loop and a while loop that gets the job done.

// using a for loop
const range = function(start, end, step) {
  let arr = [];
  for (i = start; i <= end; i += step){
     arr.push(i);
  };
  return arr;
}

console.log("Using a for loop: ", range(0, 10, 2)); // gives [ 0, 2, 4, 6, 8, 10]

// using a while loop
const range2 = function(start, end, step) {
  let arr = [];
  let i = start
  while (i <= end){
     arr.push(i); 
     i += step;
  };
  return arr;
}

console.log("Using a while loop: ", range2(0, 10, 2)); // gives [ 0, 2, 4, 6, 8, 10]