Book Image

JavaScript from Beginner to Professional

By : Laurence Lars Svekis, Maaike van Putten, Codestars By Rob Percival
4 (5)
Book Image

JavaScript from Beginner to Professional

4 (5)
By: Laurence Lars Svekis, Maaike van Putten, Codestars By Rob Percival

Overview of this book

This book demonstrates the capabilities of JavaScript for web application development by combining theoretical learning with code exercises and fun projects that you can challenge yourself with. The guiding principle of the book is to show how straightforward JavaScript techniques can be used to make web apps ranging from dynamic websites to simple browser-based games. JavaScript from Beginner to Professional focuses on key programming concepts and Document Object Model manipulations that are used to solve common problems in professional web applications. These include data validation, manipulating the appearance of web pages, working with asynchronous and concurrent code. The book uses project-based learning to provide context for the theoretical components in a series of code examples that can be used as modules of an application, such as input validators, games, and simple animations. This will be supplemented with a brief crash course on HTML and CSS to illustrate how JavaScript components fit into a complete web application. As you learn the concepts, you can try them in your own editor or browser console to get a solid understanding of how they work and what they do. By the end of this JavaScript book, you will feel confident writing core JavaScript code and be equipped to progress to more advanced libraries, frameworks, and environments such as React, Angular, and Node.js.
Table of Contents (19 chapters)
16
Other Books You May Enjoy
17
Index

Loops and arrays

If you are not convinced of how extremely useful loops are by now, have a look at loops and arrays. Loops make life with arrays a lot more comfortable.

We can combine the length property and the condition part of the for loop or while loop to loop over arrays. It would look like this in the case of a for loop:

let arr = [some array];
for (initialize variable; variable smaller than arr.length; statement) {
  // code to be executed
}

Let's start with a simple example that is going to log every value of the array:

let names = ["Chantal", "John", "Maxime", "Bobbi", "Jair"];
for (let i = 0; i < names.length; i ++){
  console.log(names[i]);
}

This will output:

Chantal
John
Maxime
Bobbi
Jair

We use the length property to determine the maximum value of our index. The index starts counting at 0, but the length does not. The index is always one smaller than the length. Hence, we loop over...