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

do while loops

In some cases, you really need the code block to be executed at least once. For example, if you need valid user input, you need to ask at least once. The same goes for trying to connect with a database or some other external source: you will have to do so at least once in order for it to be successful. And you will probably need to do so as long as you did not get the result you needed. In these cases, you can use a do while loop.

Here is what the syntax looks like:

do {
  // code to be executed if the condition is true
} while (condition);

It executes what is within the do block, and then after that it evaluates the while. If the condition is true, it will execute what is in the do block again. It will continue to do so until the condition in the while changes to false.

We can use the prompt() method to get user input. Let's use a do while loop to ask the user for a number between 0 and 100.

let number;
do {
  number = prompt("Please...