react-native-number-please/src/utils/range.ts

React Native number picker

export default function range(start: number, end: number, step = 1) {
  // Test that the first 3 arguments are finite numbers.
  // Using Array.prototype.every() and Number.isFinite().
  const allNumbers = [start, end, step].every(Number.isFinite);

  // Throw an error if any of the first 3 arguments is not a finite number.
  if (!allNumbers) {
    throw new TypeError('range() expects only finite numbers as arguments.');
  }

  // Ensure the step is always a positive number.
  if (step <= 0) {
    throw new Error('step must be a number greater than 0.');
  }

  // When the start number is greater than the end number,
  // modify the step for decrementing instead of incrementing.
  if (start > end) {
    step = -step;
  }

  // Determine the length of the array to be returned.
  // The length is incremented by 1 after Math.floor().
  // This ensures that the end number is listed if it falls within the range.
  const length = Math.floor(Math.abs((end - start) / step)) + 1;

  // Fill up a new array with the range numbers
  // using Array.from() with a mapping function.
  // Finally, return the new array.
  return Array.from(Array(length), (x, index) => start + index * step);
}