var length = 16; // Number
var bigLength = BigInt(16); // BigInt
var lastName = 'Johnson'; // String
var x = { firstName: 'John', lastName: 'Doe' }; // Object
var nullValue = null; // null
var undefinedValue = undefined; // undefined
var booleanValue = true; // Boolean
var newSymbol = Symbol("I'm new in es6!"); // Symbol
var notNumber = NaN; // Number

// the type of every variable in javascript can be checked using typeof(var)