How to check if character is a letter in Javascript?

Question

I am extracting a character in a Javascript string with:

var first = str.charAt(0);

and I would like to check whether it is a letter. Strangely, it does not seem like such functionality exists in Javascript. At least I cannot find it.

How can I test this?

Answer 1

I don't believe there is a built-in function for that. But it's easy enough to write with a regex

function isLetter(str) {
  return str.length === 1 && str.match(/[a-z]/i);
}