Count the number of vowel in javascript

Vowel count.js

function VowelCount(str) { 
	var count =  str.split('').map(function (item) {
      return item.match(/[aeiouAEIOU]/) ? item : '';
    }).join('');
  return count.length;
         
}
   
// keep this function call here 
// to see how to enter arguments in JavaScript scroll down
VowelCount(str);