介绍

给定 10 个数字，返回格式化为 (XXX) XXX-XXXX 的电话号码。

实现

JavaScript

// function that takes 10 digits and returns a string of the formatted phone number
// e.g.: 1234567890 -> (123) 456-7890

const formatPhoneNumber = (numbers) => {
  const numbersString = numbers.toString()
  if ((numbersString.length !== 10) || isNaN(numbersString)) {
    // return "Invalid phone number."
    throw new TypeError('Invalid phone number.')
  }
  const arr = '(XXX) XXX-XXXX'.split('')
  Array.from(numbersString).forEach(n => {
    arr[arr.indexOf('X')] = n
  })
  return arr.join('')
}