Book Image

Learning Object-Oriented Programming

By : Gaston C. Hillar
Book Image

Learning Object-Oriented Programming

By: Gaston C. Hillar

Overview of this book

Table of Contents (16 chapters)
Learning Object-Oriented Programming
About the Author
About the Reviewers

Understanding that functions are objects in JavaScript

We will use Chrome Developer Tools (CDT), as the main JavaScript console. However, you can run the examples in any other browser that provides a JavaScript console.

Functions are first-class citizens in JavaScript. In fact, functions are objects in JavaScript. When we type the following lines in a JavaScript console, we create a new function object. Thus, calculateArea is an object, and its type is function. Notice the results of writing the following lines in a JavaScript console. The displayed type for calculateArea is a function, as follows:

function calculateArea(width, height) { return width * height; }

The calculateArea function receives two arguments: width and height. It returns the width value multiplied by the height value. The following line calls the calculateArea function and saves the returned number in the rectangleArea variable:

var rectangleArea = calculateArea(300, 200);