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Functions

Functions

Section titled “Functions”

Introduction

Section titled “Introduction”

Functions are the building blocks of JavaScript. They are first-class citizens — they can be assigned to variables, passed as arguments, and returned from other functions.

Learning Objectives

Section titled “Learning Objectives”
  • Write functions using declarations, expressions, and arrow syntax
  • Understand parameters, arguments, and the arguments object
  • Master higher-order functions, callbacks, and closures
  • Use IIFEs, recursion, and pure functions

Learning Path

Section titled “Learning Path”
Declarations → Expressions → Arrow Functions → Parameters → Callbacks → HOFs → Closures → Recursion → IIFE → Pure Functions

Topics Covered

Section titled “Topics Covered”
TopicDescription
Function DeclarationClassic function definition
Function ExpressionFunctions as values
Arrow FunctionsConcise ES6 syntax
Anonymous FunctionsFunctions without names
Named FunctionsNamed function expressions
Callback FunctionsFunctions passed as arguments
Higher-Order FunctionsFunctions that take/return functions
Pure FunctionsDeterministic, side-effect-free
RecursionFunctions calling themselves
IIFEImmediately Invoked Function Expression
Default ParametersParameters with default values
Rest ParametersVariable-length arguments
arguments ObjectArray-like arguments access
Function HoistingHow functions are hoisted

Estimated Learning Time

Section titled “Estimated Learning Time”

3–4 hours

Section titled “Related Topics”
  • Scope
  • Execution Context
  • Closures