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
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17
Index

Loops and objects

We have just seen how to loop over the values of an array, but we can also loop over the properties of an object. This can be helpful when we need to go over all the properties but don't know the exact properties of the object we are iterating over.

Looping over an object can be done in a few ways. We can use the for in loop to loop over the object directly, or we can convert the object to an array and loop over the array. We'll consider both in the following sections.

for in loop

Manipulating objects with loops can also be done with another variation of the for loop, the for in loop. The for in loop is somewhat similar to the for of loop. Again here, we need to specify a temporary name, also referred to as a key, to store each property name in. We can see it in action here:

let car = {
  model: "Golf",
  make: "Volkswagen",
  year: 1999,
  color: "black",
};
for (let prop in car){
  console.log(car[prop]);...