Looping Range Invalid array

byMR

April 12, 2024

In this challenge, you will build a function that creates an array for a given start, end, and step parameter.

The function takes three integer parameters: start, end, and step.
The function should return an array of numbers from start to end, counting by step.

The function checks for incorrect parameters by ensuring that;

start, end, or step are defined
start is not greater than end
step is greater than zero
If any of these parameters are not met, the function should return an empty array [].

My code:

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

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

RangeError: Invalid array length

>Solution :

You forgot to do the validations described.

While doing the validations, you can use early return to get a code with more readability.

start, end, or step are defined

if (start === undefined || end === undefined || step === undefined) {
  return []
}

start is not greater than end

if (start > end) {
  return []
}

step is greater than zero

if (step <= 0) {
  return []
}

Final function:

function range (start, end, step) {
  if (start === undefined || end === undefined || step === undefined) {
    return []
  }

  if (start > end) {
    return []
  }

  if (step <= 0) {
    return []
  }

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