Data Types

• JavaScript variables can hold different data types
• In JavaScript you have two categories of data types: primitives or value types and reference types

Primitive Data Types/Value Data Types

• String
• Number
• Boolean
• undefined
• null
• Symbol (From ES6)

Literal

• Literals represent values in JavaScript. These are fixed values that you literally provide in your script.

String

• String is a sequence of character
• You can single or double quotes

let name = "kumar"; //String Literal

Number

• Can be with or without decimal
• Represent both integers and floating-point numbers

let height = 6; //Number Literal

Boolean

• Possible values are true and false let isGraduated = true; //Boolean Literal

Undefined

• if you don't initialize a variable, the default value is undefined.
• Undefined is a type and you can also assign it a value undefined.
• The meaning of undefined is value is not assigned.

let bikeName;
let bikeName = undefined;

Null

• Use null when the value is not known
• Use null in situations when you want to explicitly clear the value of a variable.
• It’s just a special value which represents nothing, empty or value unknown.
• The result of typeof null is object. That’s an officially recognized error in typeof, coming from very early days of JavaScript and kept for compatibility.

let selectedCar = null;
selectedCar = "maruti"
selectedCar = null;