index.js

'use strict'

/* global SharedArrayBuffer, Atomics */

if (typeof SharedArrayBuffer !== 'undefined' && typeof Atomics !== 'undefined') {
  const nil = new Int32Array(new SharedArrayBuffer(4))

  function sleep (ms) {
    // also filters out NaN, non-number types, including empty strings, but allows bigints
    const valid = ms > 0 && ms < Infinity 
    if (valid === false) {
      if (typeof ms !== 'number' && typeof ms !== 'bigint') {
        throw TypeError('sleep: ms must be a number')
      }
      throw RangeError('sleep: ms must be a number that is greater than 0 but less than Infinity')
    }

    Atomics.wait(nil, 0, 0, Number(ms))
  }
  module.exports = sleep
} else {

  function sleep (ms) {
    // also filters out NaN, non-number types, including empty strings, but allows bigints
    const valid = ms > 0 && ms < Infinity 
    if (valid === false) {
      if (typeof ms !== 'number' && typeof ms !== 'bigint') {
        throw TypeError('sleep: ms must be a number')
      }
      throw RangeError('sleep: ms must be a number that is greater than 0 but less than Infinity')
    }
    const target = Date.now() + Number(ms)
    while (target > Date.now()){}
  }

  module.exports = sleep

}