Get the number of a character in a string

const characterCount = (str, char) => str.split(char).length - 1;

// Or
const characterCount = (str, char) => str.replace(new RegExp(String.raw`[^${char}]`, 'g'), '').length;

const characterCount = (str: string, char: string): number => str.split(char).length - 1;

// Or
const characterCount = (str: string, char: string): number => str.replace(new RegExp(String.raw`[^${char}]`, 'g'), '').length;

characterCount('192.168.1.1', '.'); // 3
characterCount('star wars', 's'); // 2