1.3-naming-convension.js

// JavaScript is CASE SENSITIVE

let firstname = 'Saidur'; // lower case
let first_name = 'Saidur'; // snake_case
let FirstName = 'Saidur'; // PascalCase
let firstName = 'Saidur'; // camelCase

// https://www.robinwieruch.de/javascript-naming-conventions