Javascript validation regex for names

Question

I am looking to accept names in my app with letters and hyphens or dashes, i based my code on an answer i found here and coded that:

function validName(n){
  var nameRegex = /^[a-zA-Z\-]+$/;
  if(n.match(nameRegex) == null){
    return "Wrong";
  }
  else{
    return "Right";
  }
}

the only problem is that it accepts hyphen as the first letter (even multiple ones) which i don't want. thanks

Answer 1

Use negative lookahead assertion to avoid matching the string starting with a hyphen. Although there is no need to escape - in the character class when provided at the end of character class. Use - removed character class for avoiding - at ending or use lookahead assertion.

var nameRegex = /^(?!-)[a-zA-Z-]*[a-zA-Z]$/;
// or
var nameRegex = /^(?!-)(?!.*-$)[a-zA-Z-]+$/;

var nameRegex = /^(?!-)[a-zA-Z-]*[a-zA-Z]$/;
// or
var nameRegex1 = /^(?!-)(?!.*-$)[a-zA-Z-]+$/;

function validName(n) {
  if (n.match(nameRegex) == null) {
    return "Wrong";
  } else {
    return "Right";
  }
}

function validName1(n) {
  if (n.match(nameRegex1) == null) {
    return "Wrong";
  } else {
    return "Right";
  }
}

console.log(validName('abc'));
console.log(validName('abc-'));
console.log(validName('-abc'));
console.log(validName('-abc-'));
console.log(validName('a-b-c'));

console.log(validName1('abc'));
console.log(validName1('abc-'));
console.log(validName1('-abc'));
console.log(validName1('-abc-'));
console.log(validName1('a-b-c'));

FYI : You can use RegExp#test method for searching regex match and which returns boolean based on regex match.

if(nameRegex.test(n)){
  return "Right";
}
else{
  return "Wrong";
}

---

UPDATE : If you want only single optional - in between words, then use a 0 or more repetitive group which starts with -as in @WiktorStribiżew answer .

var nameRegex = /^[a-zA-Z]+(?:-[a-zA-Z]+)*$/;