count vowels in a string javascript

Count Vowels in a String using Javascript#

Counting the number of vowels in a given string is a common task in programming. In Javascript, we can do this by looping through each character in the string and checking if it is a vowel or not.

Method 1:#

One way to count vowels in a string is to use a regular expression to match all the vowels and then count the number of matches.

function countVowels(str) {
  return (str.match(/[aeiou]/gi) || []).length;
}

• str.match(/[aeiou]/gi) matches all the vowels in the string.
• (str.match(/[aeiou]/gi) || []) returns an array of matches or an empty array if there are none.
• (str.match(/[aeiou]/gi) || []).length returns the length of the array, which is the number of vowels in the string.

Method 2:#

Another way to count vowels in a string is to loop through each character in the string and check if it is a vowel.

function countVowels(str) {
  var count = 0;
  for (var i = 0; i < str.length; i++) {
    if (/[aeiou]/.test(str[i])) {
      count++;
    }
  }
  return count;
}

• var count = 0; initializes a variable to keep track of the number of vowels.
• for (var i = 0; i < str.length; i++) loops through each character in the string.
• if (/[aeiou]/.test(str[i])) checks if the current character is a vowel.
• count++; increments the count if the current character is a vowel.
• return count; returns the total number of vowels in the string.

Usage:#

To use the function, simply call it with a string as an argument:

var str = "Hello World";
var vowels = countVowels(str);
console.log(vowels); // output: 3