What is Pure Functions Javascript

In this article, we will see what is pure functions javascript.

Javascript Function

A function is a block of code, meant to perform a specific task.
Whenever we want to perform some specific task, we create a function.

Why function? function is created

• To divide a larger problem into smaller tasks or modules(manageability).
• For reusability(i.e. once a function is defined, it can be used multiple times).
• For abstraction(i.e hiding the way how tasks are done) (creating libraries).

Types of function

There are many ways in which we can create a function in javascript:

• Function declaration
• Function expression
• Function constructor
• IIFE ( Immediately Invokable Function Expression)

How to create a function using Function Declaration

A function defined with function declaration must begin with the function keyword.

Syntax:

function functionname([param1, param2, ...paramN]) // function header
{
statements;
}

Example:

A function without parameters and returning value

function display()
{
document.write("Hi");
}
display();

//output: Hi

Note: Every function gets executed only when we call them.

The syntax for calling the function:

functionname([param1, param2...paramN]);

Example : display();

If we call the function many times, the function is executed many times.