41. Defining Functions: Function Declarations

A function is a block of code designed to perform a particular task. Functions allow us to reuse code (DRY principle).

Function Declaration Syntax

The most traditional way to define a function is via a function declaration. This defines the function with a specific name.

javascript function functionName(parameter1, parameter2) { // Block of code to be executed // ... }

Example: Greeting Function

javascript // 1. Declare the function function greetUser(name) { console.log('Hello, ' + name + '!'); }

// 2. Call (execute) the function greetUser('Sarah'); // Output: Hello, Sarah! greetUser('Tom'); // Output: Hello, Tom!

Hoisting

Function declarations benefit from hoisting. This means the function can be called before it appears in the code. (We will cover hoisting in depth later.)

javascript sayGoodbye(); // This works even though the function is defined below.

function sayGoodbye() { console.log('Goodbye!'); }