rhodash/src/toRange.ts

A deadly simple alternative to lodash

/**
 * Create an array of sequential numbers with end values.
 *
 * @example
 * toRange(5) // => [0, 1, 2, 3, 4, 5]
 * toRange(1, 5) // => [1, 2, 3, 4, 5]
 * toRange(0, 10, 2) // => [0, 2, 4, 6, 8, 10]
 */
export function toRange(start: number, end?: number, step?: number): number[] {
  // to avoid infinite loop, when { strict: false } and passing invalid arguments
  if (typeof start !== 'number') throw Error('start must be a number')
  if (typeof end !== 'undefined' && typeof end !== 'number') throw Error('end must be a number')
  if (typeof step !== 'undefined' && typeof step !== 'number') throw Error('step must be a number')
  if (step === 0) throw Error('step cannot be zero')

  if (end === undefined) {
    end = start
    start = 0
  }

  if (step === undefined) step = start < end ? 1 : -1

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