Course Lessons

Lesson 2 of 3

Functions and Scope

Master JavaScript functions including declarations, expressions, arrow functions, and understand how scope works.

24 minutes

Functions and Scope

Functions are reusable blocks of code that perform specific tasks.

Function Declarations

The traditional way to define a function:

function greet(name) {
  return `Hello, ${name}!`;
}

Arrow Functions

Modern ES6 syntax for shorter function expressions:

const greet = (name) => `Hello, ${name}!`;

Understanding Scope

Global Scope: Variables accessible everywhere
Function Scope: Variables only accessible within the function
Block Scope: Variables only accessible within {} blocks

Key Takeaway

Arrow functions are great for callbacks and short functions, while traditional functions are better when you need the this keyword.

Code Example

// Function declaration
function add(a, b) {
  return a + b;
}

// Arrow function
const multiply = (a, b) => a * b;

// Function with default parameters
const greet = (name = "Guest") => {
  return `Welcome, ${name}!`;
};

console.log(add(5, 3));        // 8
console.log(multiply(4, 2));   // 8
console.log(greet());          // Welcome, Guest!
console.log(greet("Elena"));   // Welcome, Elena!

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