Swipe to show menu

Functions help you organize and reuse code in JavaScript. A function is a named block of code that performs a specific task. You can define a function once and call it whenever needed.

There are three common ways to create functions: function declarations, function expressions, and arrow functions.

Function Declaration

A function declaration uses the function keyword followed by a name, parameters, and a block of code.


              12345
            
function add(a, b) {
  return a + b;
}

console.log(add(3, 4)); // 7

Function Expression

A function expression assigns a function to a variable.


              12345
            
const multiply = function(a, b) {
  return a * b;
};

console.log(multiply(3, 4)); // 12

Arrow Functions

Arrow functions provide a shorter and more modern syntax. They are widely used in React and Next.js.


              12345
            
const subtract = (a, b) => {
  return a - b;
};

console.log(subtract(5, 2)); // 3

For simple expressions, you can return a value without writing return:


              123
            
const divide = (a, b) => a / b;

console.log(divide(10, 2)); // 5

Function Scope

Variables declared inside a function are only available within that function. This is called local scope.


              123456
            
function greet(name) {
  const message = "Hello, " + name + "!";
  return message;
}

console.log(greet("Sam")); // Hello, Sam!

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 9

Ask AI

Ask anything or try one of the suggested questions to begin our chat

Functions