Range Function

const range = (start, end, step = 1) => {
  const numbers = [];

  if (typeof end === 'undefined') {
    end = start;
    start = 0;
  }

  for (let i = start; i < end; i += step) {
    numbers.push(i);
  }

  return numbers;
};

JavaScript's developers often need a quick and efficient way to generate a sequence of numbers. Whether you're creating an array of values for a loop or generating a series of steps, a range function can be incredibly useful.

Many popular solutions, even Lodash's _.range, are not efficient if we read the V8 blog and understand how Arrays work. I will describe these topics in a future post.

Examples

range(5); // Output: [0, 1, 2, 3, 4]

range(2, 8); // Output: [2, 3, 4, 5, 6, 7]

range(1, 10, 2); // Output: [1, 3, 5, 7, 9]