Foundations Updated 2026-09 View as Markdown

Functions

Functions are code blocks that can have arguments, and function have their own scope.

Functions are code blocks that can have arguments, and function have their own scope. In JavaScript, functions are a very important feature of the program, and especially the fact that they can access local variables of a parent function (this is called a closure).

There are two ways to define functions in JavaScript - named functions and anonymous functions.

To define a named function, we use the function statement as follows:

function greet(name)
{
    return "Hello " + name + "!";
}

console.log(greet("Eric"));      // prints out Hello Eric!

In this function, the name argument to the greet function is used inside the function to construct a new string and return it using the return statement.

To define an anonymous function, we can alternatively use the following syntax:

let greet = function(name)
{
    return "Hello " + name + "!";
}

console.log(greet("Eric"));      // prints out Hello Eric!

let greet = function(name)
{
    return "Hello " + name + "!";
}

console.log(greet("Eric"));      // prints out Hello Eric!