Count vowels available in string

VowelCount.js

/*
  VowelCount is javascript function which takes string as input
  return count of vowels available or 0 if no vowels available
 */

const VowelCount = (str) =>{
    const vowelArray = ['a', 'e', 'i', 'o', 'u'];
    let counter = 0;
    for (let i = 0; i < vowelArray.length; i++) {
        for (let j = 0; j < str.length; j++) {
            str[j].toLowerCase() == vowelArray[i] && ++ counter 
        }
    }
    return counter;
}

const VowelCount_Regex = (str) =>{
   return str.match(/a|e|i|o|u/gi) ? str.match(/a|e|i|o|u/gi).length : 0;
}

console.log(VowelCount("All cows eat grass")) //5
console.log(VowelCount("Bxt")) // 0

console.log(VowelCount_Regex("All cows eat grass")) // 5
console.log(VowelCount_Regex("Bxt")) // 0