JavaScript Tutorial
Variables and Constants in JavaScript
Table of Contents
- Introduction
- What is a JavaScript Variable?
- Declaring a Variable in JavaScript
- Initializing a Variable in JavaScript
- Changing the Value of a Variable
- JavaScript Data Types
- JavaScript Variable Scope
- What is a JavaScript Constant?
- Declaring Constants in JavaScript
- Examples of Const in JavaScript
FAQs about JavaScript Variables and Constants
var is function-scoped, allows redeclaration, and is prone to hoisting issues.
let is block-scoped and does not permit redeclaration.
const is block-scoped, immutable, and must be initialized upon declaration.
No, the reference of a constant cannot be changed. However, the contents of objects and arrays declared with const can be modified.
Using a variable without declaring it results in an error in strict mode. Without strict mode, it creates an implicit global variable, which is not recommended.
Yes, variable names are case-sensitive. For example, myVar and myvar are treated as different variables.
Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their scope during compilation. Variables declared with var are hoisted but not initialized, while let and const are hoisted but inaccessible before their declaration due to the temporal dead zone.
