Question

function isVowel(char){

    if(typeof char == 'string' && char.length > 1){
        console.log('not a char');
        return 'not a char';
    } else {
        if (char.toLowerCase() === ('a'||'e'||'i'||'o'||'u')){
            console.log(char, true);
            return true;
        } else {
            console.log(char, false);
            return false;
        }
    }
}

document.writeln(isVowel('a'));
document.writeln(isVowel('e'));
document.writeln(isVowel('l'));

the result is: true, false, false;

it should be: true, true, false;

Can anyone help me why this is happening?

I’m just barely learning JavaScript…

Also, is there any way to refactor this code? I don’t want to be repeating myself for every new condition..

Answer 1

('a'||'e'||'i'||'o'||'u') is equal to "a"

To confirm the above, just try it using the console, or:

console.log(('a'||'e'||'i'||'o'||'u'));

My suggestion:

' aeiou'.indexOf(char) > 0

Complete version:

function isVowel(char){

    if(typeof char == 'string' && char.length > 1){
        console.log('not a char');
        return 'not a char';
    } else {
        if (' aeiou'.indexOf(char) > 0){
            console.log(char, true);
            return true;
        } else {
            console.log(char, false);
            return false;
        }
    }
}

document.writeln(isVowel('a'));
document.writeln(isVowel('e'));
document.writeln(isVowel('l'));

Refactored version:

function isVowel(char)
{
    return ((typeof char == 'string') && (char.length == 1) && ('aeiou'.indexOf(char.toLowerCase()) != -1));
}