Counting number of vowels in a string with JavaScript

Question

I\'m using basic JavaScript to count the number of vowels in a string. The below code works but I would like to have it cleaned up a bit. Would using .includes()

Answer 1

    (A)   
     const countVowels = data => [...data.toLowerCase()].filter(char => 'aeiou'.includes(char)).length;

    (B)    
      const countVowels = data => data.toLowerCase().split('').filter(char => 'aeiou'.includes(char)).length;

    countVowels("Stackoverflow") // 4 

Answer 2

Just use this function [for ES5] :

function countVowels(str){
    return (str.match(/[aeiou]/gi) == null) ? 0 : str.match(/[aeiou]/gi).length;        
}

Will work like a charm

Answer 3

The following works and is short:

 function countVowels(str) {
 return ( str = str.match(/[aeiou]/gi)) ? str.length : 0;
}


console.log(countVowels("abracadabra")); // 5
console.log(countVowels(""));            // 0

Answer 4

You can actually do this with a small regex:

function getVowels(str) {
  var m = str.match(/[aeiou]/gi);
  return m === null ? 0 : m.length;
}

This just matches against the regex (g makes it search the whole string, i makes it case-insensitive) and returns the number of matches. We check for null incase there are no matches (ie no vowels), and return 0 in that case.

Answer 5

As the introduction of forEach in ES5 this could be achieved in a functional approach, in a more compact way, and also have the count for each vowel and store that count in an Object.

function vowelCount(str){
  let splitString=str.split('');
  let obj={};
  let vowels="aeiou";
  splitString.forEach((letter)=>{
    if(vowels.indexOf(letter.toLowerCase())!==-1){
      if(letter in obj){
        obj[letter]++;
      }else{
        obj[letter]=1;
      }
    }   

 });
 return obj;    
}

Answer 6

Function vowels(str){
   let count=0;
   const checker=['a','e','i','o','u'];
   for (let char of str.toLowerCase){
      if (checker.includes(char)){
        count++;
      }
   return count;
}


Function vowels(str){
   const match = str.match(/[aeiou]/gi);
   return match ? match.length : 0 ;
}