JavaScript Functions - Basics and Syntax

Functions are a fundamental concept in JavaScript that allow you to encapsulate and reuse blocks of code. In this guide, we'll explore the basics of JavaScript functions and their syntax.

Defining Functions

You can define a function in JavaScript using the function keyword. Here's a basic example:

function greet() {
console.log("Hello, world!");
// Calling the function

In this example, we've defined a function called greet that simply logs "Hello, world!" to the console. To use the function, we call it by writing its name followed by parentheses: greet().

Function Parameters

Functions can accept parameters, which are values you pass into the function to use within its block. Here's an example with parameters:

function greetPerson(name) {
console.log("Hello, " + name + "!");
// Calling the function with a parameter

In this case, the greetPerson function accepts a parameter named name, and we pass "John" as the argument when calling the function.

Return Statement

Functions can return values using the return statement. Here's an example:

function add(a, b) {
return a + b;
// Calling the function and storing the result
let sum = add(3, 5);
console.log("Sum: " + sum);

The add function takes two parameters and returns their sum. We store the result in a variable sum when calling the function.

Anonymous Functions and Function Expressions

You can define functions without a name, known as anonymous functions, and assign them to variables. Here's an example:

let multiply = function(a, b) {
return a * b;
// Calling the anonymous function
let product = multiply(4, 6);
console.log("Product: " + product);

In this case, we've assigned an anonymous function to the multiply variable and called it as usual.


Functions are a crucial building block of JavaScript. They allow you to encapsulate and reuse code, making your programs more organized and maintainable. Understanding the basics and syntax of JavaScript functions is essential for any JavaScript developer.

Happy coding!