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Functions and Scope

Beginner
90 XP
35 min
Lesson Content

Functions and Scope

Functions are reusable blocks of code that perform specific tasks. They help organize code and avoid repetition.

Function Declaration

function greet(name) {
  return 'Hello, ' + name + '!';
}
console.log(greet('Alice')); // Hello, Alice!

Arrow Functions

const add = (a, b) => {
  return a + b;
};

// Shorthand for single expression
const multiply = (a, b) => a * b;

Scope

  • Global scope: Variables accessible everywhere
  • Local scope: Variables inside functions
  • Block scope: Variables inside {} blocks (let, const)

Return Values

function calculateArea(width, height) {
  return width * height;
}
let area = calculateArea(5, 10); // 50
Example Code

Create functions to perform calculations

// Function to add two numbers
function add(a, b) {
  return a + b;
}

// Function to calculate area
function calculateArea(width, height) {
  return width * height;
}

// Arrow function to greet
const greet = (name) => {
  return 'Hello, ' + name + '!';
};

// Test the functions
console.log('Sum:', add(5, 3));
console.log('Area:', calculateArea(4, 6));
console.log(greet('World'));

Expected Output:

Sum: 8
Area: 24
Hello, World!
Study Tips
  • •Read the theory content thoroughly before practicing
  • •Review the example code to understand key concepts
  • •Proceed to the Practice tab when you're ready to code