regex - How do I check for vowels in JavaScript?

Question

I'm supposed to write a function that takes a character (i.e. a string of length 1) and returns true if it is a vowel, false otherwise. I came up with two functions, but don't know which one is better performing and which way I should prefer. The one with RegEx is way simpler but I am unsure whether I should try to avoid using RegEx or not?

Without RegEx:

function isVowel(char) {
  if (char.length == 1) {
    var vowels = new Array("a", "e", "i", "o", "u");
    var isVowel = false;

    for (e in vowels) {
      if (vowels[e] == char) {
        isVowel = true;
      }
    }

    return isVowel;
  }
}

With RegEx:

function isVowelRegEx(char) {
  if (char.length == 1) {

    return /[aeiou]/.test(char);
  }
}

Answer 1

benchmark

I think you can safely say a for loop is faster.

I do admit that a regexp looks cleaner in terms of code. If it's a real bottleneck then use a for loop, otherwise stick with the regular expression for reasons of "elegance"

If you want to go for simplicity then just use

function isVowel(c) {
    return ['a', 'e', 'i', 'o', 'u'].indexOf(c.toLowerCase()) !== -1
}