javascript count number characters in string code example

Example 1: count occurrences of character in string javascript

var temp = "This is a string.";
var count = (temp.match(/is/g) || []).length;
console.log(count);

Output: 2

Explaination : The g in the regular expression (short for global) says to search the whole string rather than just find the first occurrence. This matches 'is' twice.

Example 2: count vowels in a string javascript

// BEST and FASTER implementation using regex
const countVowels = (str) => (str.match(/[aeiou]/gi) || []).length