indexOf

indexOf.js

// Use index of to check contents of array. 
// A function that takes a character (i.e. a string of length 1) and returns true if it is a vowel, false otherwise.

function isVowel(letter) { 
  vowels = ['a','e','i','o','u'];
  var result = vowels.indexOf(letter)
  if (result >= 0) { 
    return true;
  } 
  else { 
    return false;
  } 
}