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 }