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

count = function(a) {
  //var a=document.getElementById("t");
  console.log(a); //to see input string on console
  n = a.length;
  console.log(n); //calculated length of string
  var c = 0;
  for (i = 0; i < n; i++) {
    if ((a[i] == "a") || (a[i] == "e") || (a[i] == "i") || (a[i] == "o") || (a[i] == "u")) {
      console.log(a[i]); //just to verify
      c += 1;
    }
  }

  document.getElementById("p").innerText = c;
}

<p>count of vowels </p>
<p id="p"></p>
<input id="t" />
<input type="button" value="count" onclick="count(t.value)" />

Answer 2

This could also be solved using .replace() method by replacing anything that isn't a vowel with an empty string (basically it will delete those characters) and returning the new string length:

function vowelCount(str) {
  return str.replace(/[^aeiou]/gi, "").length;
};

or if you prefer ES6

const vowelCount = (str) => ( str.replace(/[^aeiou]/gi,"").length )

Answer 3

One more method (using reduce):

   function getVowels(str) {
     return Array.from(str).reduce((count, letter) => count + 'aeiou'.includes(letter), 0);
   }

Answer 4

const containVowels = str => {
  const helper = ['a', 'e', 'i', 'o', 'u'];

  const hash = {};

  for (let c of str) {
    if (helper.indexOf(c) !== -1) {
      if (hash[c]) {
        hash[c]++;
      } else {
        hash[c] = 1;
      }
    }
  }

  let count = 0;
  for (let k in hash) {
    count += hash[k];
  }

  return count;
};

console.log(containVowels('aaaa'));

Answer 5

You can convert the given string into an array using the spread operator, and then you can filter() the characters to only those which are vowels (case-insensitive).

Afterwards, you can check the length of the array to obtain the total number of vowels in the string:

const vowel_count = string => [...string].filter(c => 'aeiou'.includes(c.toLowerCase())).length;

console.log(vowel_count('aaaa'));            // 4
console.log(vowel_count('AAAA'));            // 4
console.log(vowel_count('foo BAR baz QUX')); // 5
console.log(vowel_count('Hello, world!'));   // 3

Answer 6

Use this function to get the count of vowels within a string. Works pretty well.

function getVowelsCount(str)
{
  //splits the vowels string into an array => ['a','e','i','o','u','A'...]
  let arr_vowel_list = 'aeiouAEIOU'.split(''); 


  let count = 0;
  /*for each of the elements of the splitted string(i.e. str), the vowels list would check 
    for any occurence and increments the count, if present*/
  str.split('').forEach(function(e){
  if(arr_vowel_list.indexOf(e) !== -1){
   count++;} });


   //and now log this count
   console.log(count);}


//Function Call
getVowelsCount("World Of Programming");

Output for the given string would be 5. Try this out.

//Code -

  function getVowelsCount(str)
   {
     let arr_vowel_list = 'aeiouAEIOU'.split(''); 
     let count = 0;
     str.split('').forEach(function(e){
     if(arr_vowel_list.indexOf(e) !== -1){
     count++;} });
     console.log(count);
   }