Self-invoking functions, also known as Immediately Invoked Function Expressions (IIFE), are a powerful feature in JavaScript. They allow functions to execute as soon as they are defined. This pattern is particularly useful for initializing applications, avoiding pollution of the global namespace, and managing private variables within a localized scope.

Basic Syntax

A self-invoking function is defined using function syntax, enclosed in parentheses, followed by another set of parentheses that causes it to be invoked immediately:

Example 1: Basic Self-Invoking Function

Explanation:

• Function Enclosure: The function is enclosed in parentheses, which makes it a function expression rather than a declaration.
• Immediate Invocation: The additional parentheses () at the end of the function expression cause it to execute immediately after it's defined.
• Local Scope: The variable message is local to the function scope, protecting it from external access and modifications.

Example 2: Self-Invoking Function with Parameters

Explanation:

• Passing Parameters: This IIFE is immediately invoked with the parameters "Hello" and "John".
• Function Execution: The function concatenates and logs the provided arguments, demonstrating how parameters can be passed to and used within an IIFE.

Why Use Self-Invoking Functions?

• Namespace Management: By executing within their own scope, IIFEs prevent cluttering the global namespace, reducing the risk of variable and function name conflicts.
• Immediate Execution: They are executed immediately after their creation, making them ideal for initialization tasks and setting up environments.
• Privacy: Variables and functions defined within an IIFE are not accessible from the outside world, enhancing security and privacy.