How do I return -1 using match() method if a search is not found?

Question

//Write a JavaScript function that accepts a string as a parameter and counts the number of vowels within the string.

function countVowels(string) {
var vowels = [],
regEx = /[aeiou]/gi,
counter = 0;

if(string === undefined) string = '';

vowels = string.match(regEx);
counter = vowels.length;
return vowels === null ? -1 : counter;
}

console.log('The quick brown fox') // logs 5

But I want the output to be -1 if a vowel is not found in the string. I have tried to use an if else statement like this:

if(counter > 0) return counter; else return -1; // This doesn't work too. Outputs a blank screen

I don't know if it is because of the match() method I used. I googled the return value of the match() method if no match is found and it is 'null'. That is why I used it in my code above:

return vowel === null ? -1 : counter; //outputs a blank screen

but it still doesn't work. What's the problem?

Answer 1

You can also use the optional chaining(?.) operator.
counter = vowel?.length
So instead of getting an error message because of null, undefined is returned.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining

Nullish coalescing operator (??) can also be used in concert with the optional chaining operator. To make code more concise.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Nullish_coalescing_operator

Answer 2

The problem is that when there is no vowels you cant assign a value to counter thus it will throw an error.
This would work
function countVowels(string) {
var vowels = [],
regEx = /[aeiou]/gi,

if(string === undefined) string = '';

vowels = string.match(regEx);

return vowels === null ? -1 : vowels.length;

Answer 3

Eddy Ricchy This might help
https://code.sololearn.com/WLJjqJqxgtuB/?ref=app

Answer 4

C K Thanks for your explanation. I understand now.

Answer 5

ODLNT I looked up the link you sent. It was very resourceful. I have a better understanding of how optional chaining and nullish coalescing operators works now. Thank you.