SOLID PRINCIPLES IN JAVA SCRIPT

 Understanding JavaScript Functions 

 Introduction

JavaScript is the heart of front-end logic.
Two of its most important concepts are Functions and Arrays.
Understanding these makes you a confident developer who can write clean, reusable, and efficient code.

“Functions organize your logic. Arrays organize your data.”

JavaScript Functions

 What is a Function?

A function is a block of code designed to perform a specific task.
It runs when it is called or invoked.

Function Syntax:

function functionName(parameter1, parameter2) {

  // code to be executed

  return result;

}

Example 1 — Simple Function

function greet() {

  console.log("Welcome to JavaScript!");

}

greet(); // Output: Welcome to JavaScript!

Explanation:

• function greet() → defines the function

• greet(); → calls the function

Example 2 — Function with Parameters

function calculateSalary(basic, bonus) {

  return basic + bonus;

}

console.log(calculateSalary(30000, 5000)); // Output: 35000

Here,

• basic and bonus are parameters (inputs).

• The function returns total salary.

Example 3 — Arrow Function (Modern JS)

const addNumbers = (a, b) => a + b;

console.log(addNumbers(5, 10)); // Output: 15

Arrow functions are shorter and cleaner.
Used widely in React (like event handlers, useEffect, etc).

Example 4 — Function Calling Another Function

function getHRA(basic) {

  return basic * 0.3;

}

function calculateTotalSalary(basic) {

  const hra = getHRA(basic);

  return basic + hra;

}

console.log(calculateTotalSalary(20000)); // Output: 26000

You can call one function inside another to organize calculations.

Conclusion — JavaScript Functions

avaScript functions are the core building blocks of any web application.
They help you write reusable, structured, and clean code that performs specific tasks efficiently.

In Simple Words:

A function is a small, independent block of code that takes inputs (parameters),
performs an operation, and returns an output — used again and again wherever needed.

Key Points Summary

• Functions reduce code repetition and improve maintainability.

• They can be named, anonymous, or arrow functions depending on the use case.

• Functions can also be passed as arguments (callbacks) or return other functions (higher-order).

• Modern JavaScript (especially React) heavily depends on arrow functions and functional patterns.

• Writing clear, modular functions makes your code readable, testable, and scalable.