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Function Factory

Write reusable code with functions. Learn declarations, arrow functions, scope, hoisting, and callbacks.

Prerequisites:🔀Flow Control
1

Why Functions Exist

Discover why programmers invented functions and how they save you from writing the same code over and over.

2

Function Declarations

Learn how to declare and call your first function using the function keyword.

3

Parameters & Return Values

Learn how to pass data into functions and get results back out.

4

Arrow Functions

Learn the shorter arrow function syntax and when to use it.

5

Function Expressions

Understand function expressions, anonymous functions, and the difference between declarations and expressions.

6

Variable Scope

Understand where variables live and die — global scope, function scope, and block scope.

7

Hoisting

Learn how JavaScript hoists declarations before running your code and why it matters.

8

Callbacks

Discover how to pass functions as arguments to other functions and unlock powerful patterns.

9

Capstone: Utility Library

Build a set of reusable utility functions that combine everything you've learned about functions.

10

Codelab: Form Validator

Build a real form validation system from scratch using everything you've learned about functions.