如何通过正则表达式验证名字？

Question

I'm writing a registration page and I need to ask the user for his first name.

I want him to have the option of not capitalizing the first letter but I don't want capital letters inside of his name, and I don't want to allow any non-letter characters as well.

Answer 1

I have written this function for your purpose.

/**
 * This function checks if first name
 * is valid. Keep in mind this is
 * not the proper solution. It will
 * work only for names written in
 * latin letters.
 * @example
 *   isFirstNameValid('Ivan')
 *   will return true.
 *   isFirstNameValid('IvaN')
 *   will return false.
 * @author Georgi Naumov
 * gonaumov@gmail.com for contacts and
 * suggestions
 **/
const isFirstNameValid = (firstName) => 
  /^[a-zA-z][a-z]+$/.test(firstName)

Edit: I have implemented a solution with unicode support for the people with a similar problem in the future. It supports Latin, Hebrew and Cyrillic. If you want to support another cultures you need to provide regexes for them inside cultures hash.

const isFirstNameValidWithUnicodeSupport = (firstName, culture = 'LATIN') => {
  const cultures = {
    HEBREW: /^[\u0590-\u05FF]{2,}$/,
    CYRILLIC: /^[\u0410-\u042F\u0430-\u044F][\u0430-\u044F]+$/,
    LATIN: /^[A-Za-z][a-z]+$/,
  };
  return  cultures[culture].test(firstName);
}

This returns true because is valid name in latin
alphabet. 
console.log(isFirstNameValidWithUnicodeSupport('Ivan'));
This returns true because is valid name in cyrillic
alphabet. 
console.log(isFirstNameValidWithUnicodeSupport('Иван', 'CYRILLIC'));
This returns false because is valid name in cyrillic
alphabet but there is a space in the end. 
console.log(isFirstNameValidWithUnicodeSupport('Иван ',  'CYRILLIC'));
This returns true because is valid name in hebrew
alphabet. 
console.log(isFirstNameValidWithUnicodeSupport('אגרת',  'HEBREW'));
This returns false because is valid name in hebrew
but is whole name containing spaces. Not only first name.
console.log(isFirstNameValidWithUnicodeSupport('אגרת בת מחלת',  'HEBREW'));

Edit2: Probably better solution is xregexp library if you want to use library for that purpose. https://github.com/slevithan/xregexp

Answer 2

You can use regex for matching string characters.

 let regex = /^[A-Za-z][az]+/g; let name = "Mark"; let match = regex.exec(name); if(match && match[0].length === name.length){ console.log(match[0]); // Mark } else{ console.log("Invalid name"); } name = "mArk"; match = regex.exec(name); if(match && match[0].length === name.length){ console.log(match[0]); } else{ console.log("Invalid name"); }

To learn more about regex.