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Asked: 2020-10-19 06:18:11 +0800 CST 2020-10-19 06:18:11 +0800 CST

How to get number of vowels in JavaScript [closed]

  • 772

How can I get the number of uppercase and lowercase vowels in a variable in JavaScript.

        var person = new Object();
        person = prompt("Introduce tus datos");

        //Numero de vocales
        var numVocales;

        for (i = 0; i < 10; i++) { 

            var vocal;

            if (i = 0){
                vocal = "a";
            }
            else if (i = 1){
                vocal = "e";
            }
            else if (i = 2){
                vocal = "i";
            }
            else if (i = 3){
                vocal = "o";
            }
            else if (i = 4){
                vocal = "u";
            }
            else if (i = 5){
                vocal = "A";
            }
            else if (i = 6){
                vocal = "E";
            }
            else if (i = 7){
                vocal = "I";
            }
            else if (i = 8){
                vocal = "O";
            }
            else if (i = 9){
                vocal = "U";
            }

            var aux = person.indexOf(vocal);

            if(aux != -1){
                numVocales++;
            }

        }


        alert(numVocales);

I can't display the information in the alert, it may be that the for is wrong. Also, I don't know if using indexOf() will get me the first matching letter. I mean, if I have ana, would using indexOf() return one or two?

javascript

2 Answers

  1. The code has quite a few bugs, so I'll try to list them and leave it to you to fix it:

    var person = new Object();

    This first line is of no use to you, you can delete it, because in the next line you assign a new value toperson

    person = prompt("Introduce tus datos");

//Numero de vocales
var numVocales;

for (i = 0; i < 10; i++) {

    This loop doesn't make much sense: up to 10 because you have 10 possible letters to search for? What you have to do is loop through the string in person.

        var vocal;

    if (i = 0){

    This is an error that often goes unnoticed by newbies: instead of using ==(compare if they are equal) you have used an assignment. What it does is that i is equal to 0 and that is the value to check. Since 0 is "false", go to the next if...

            vocal = "a";
    }
    else if (i = 1){

    Here we have the same error again, you assign 1 to i, with the difference that 1 is "true" and the comparisons are over. This means that in each iteration i is equal to 1 and the loop never ends, hanging the execution. That's why you never get to the alert.

    Clue to find vowels:

    let vocales='aeiouAEIOU'; 
let letras='ca';
if (vocales.indexOf(letras.charAt(0) != -1) { }
    • 5
  2. Best Answer

    Pablo Lozano's solution will serve you better because it is a more complete analysis of your code. I am going to give you a solution that is much shorter than what you are trying to do.

    The idea is to use regular expressions to find the occurrences of vowels ( [aeiou]) within the string. It finds them all by the modifier gand is not case sensitive by the modifier i.

    Here an example:

    var cadena = "aAeEiIoOuU son vocales";
var numeroVocales = cadena.match(/[aeiou]/gi).length;

console.log(numeroVocales);

    • 5