How do I check for vowels in JavaScript?

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
}