please help! I've been at this for hours.

I need a first name regex that accepts letters and the following special characters.

-, ', . and whitespace

However, it must NOT let the name be made up of only special characters or whitespace.

So, in essence it needs to have at least 1 letter, or start with a letter.

What I've got is this;

/^[a-zA-Z](|\s|.|'|-]*$)/i

However, it's allowing any special characters. If someone could help!

CodePudding user response：

/^(?=.*[a-z])[a-z\s.'-] $/i

(?=.*[a-z]) Require at least a ASCII letter. (positive lookahead)

You can either use (match 1 or more) or * (match 0 or more).

Note: Because of the flag i you don't need A-Za-z. It's case insensitive. So only one of them is necessary. Using both with i-flag is redundant.

Trivia: Escaping . in character set [...] is not required but optional possible (\.).

const regex = /^(?=.*[a-z])[a-z\s.'-] $/i;

console.log(regex.test('Hello World'), 'should be true');
console.log(regex.test('Hello.World'), 'should be true');
console.log(regex.test('Hello-World'), 'should be true');
console.log(regex.test(`'Hello- World.'`), 'should be true');
console.log(regex.test('Hello $ World'), 'should be false');
console.log(regex.test('Hello@World'), 'should be false');
// Min. one A-Z char required. 
console.log(regex.test(`'.- `), 'should be false');

You can also test your regex online on e.g. regexr or regex101.

CodePudding user response：

A string made up of all -, ', ., whitespace and letters is

^[-'.\sa-zA-Z] $

A string that has at least one letter in it has an unlimited number of the above sandwiching a single letter:

^[-'.\sa-zA-Z]*[a-zA-Z][-'.\sa-zA-Z]*$

You can denote the letters however you want. a-zA-Z can be just a placeholder.

CodePudding user response：

Instead of using a single regex, you could also opt to use multiple. In you scenario this would be 2:

1. Check if only whitelisted characters are used.
2. Check if at least one (ASCII) letter is used.

function validateName(name) {
  const whitelist = /^[-'.\sa-z]*$/i;
  const letter = /[a-z]/i;
  
  return whitelist.test(name) && letter.test(name);
}

console.log("John Doe",         "//=>", validateName("John Doe"));
console.log("John F. Kennedy",  "//=>", validateName("John F. Kennedy"));
console.log("Willem-Alexander", "//=>", validateName("Willem-Alexander"));
console.log("Jeanne d'Arc",     "//=>", validateName("Jeanne d'Arc"));
console.log("-' .",             "//=>", validateName("-' ."));