What are constants in JavaScript?

Constants are immutable variables which value cannot be changed. Once, you have created a constant, its value cannot be changed. While coding in JavaScript, many times you may have come across a requirement to create constants.

How do you make a constant in JavaScript?

Introduction to the JavaScript const keyword ES6 provides a new way of declaring a constant by using the const keyword. The const keyword creates a read-only reference to a value. By convention, the constant identifiers are in uppercase. Like the let keyword, the const keyword declares blocked-scope variables.

What is const object in JavaScript?

The const keyword makes a variable itself immutable, not its assigned content. When the content is an object, this means the object itself can still be altered. Therefore, it’s possible to change the content of the object that is declared with const variable, but you cannot assign a new object to a const variable.

What is difference between variable and constant in JavaScript?

var declarations are globally scoped or function scoped while let and const are block scoped. var variables can be updated and re-declared within its scope; let variables can be updated but not re-declared; const variables can neither be updated nor re-declared. They are all hoisted to the top of their scope.

How do you declare a constant?

You use the Const statement to declare a constant and set its value. By declaring a constant, you assign a meaningful name to a value. Once a constant is declared, it cannot be modified or assigned a new value. You declare a constant within a procedure or in the declarations section of a module, class, or structure.

Do I need to declare variables in JavaScript?

Before you use a variable in a JavaScript program, you must declare it. Variables are declared with the var keyword as follows. Storing a value in a variable is called variable initialization. You can do variable initialization at the time of variable creation or at a later point in time when you need that variable.