JSFiddle - React, Tailwind, and code Playground

JavaScript

function isVowel(char) {

    if (vowels.indexOf(char) >= 0) {
        return "The character \""+char+"\" is a vowel.";
    } else {
        return "The character \""+char+"\" is NOT a vowel.";
    }

}

var vowels = new Array('a','A','e','E','i','I','o','O','u','U');

alert(isVowel('e'));
alert(isVowel('f'));