Introduction

In the previous chapter, we learned how we can use arrays and objects and their helper functions. In this chapter, we will learn more about how JavaScript runs and how we can handle time-consuming operations.

When working on large-scale projects with JavaScript, often, we must deal with network requests, disk IO, and data processing. Many of these operations take time to complete, and for beginners who have just started using JavaScript, it is very difficult to understand how to retrieve the results of these time-consuming operations. This is because, unlike other languages, JavaScript has a special way of handling these operations. When coding programs, we are used to linear thinking; that is, the program executes line by line and only breaks that flow when we have loops or branches. For example, if you wanted to make a simple network request in Java, you would have to do something similar to what's shown in the following code:

import java.net.*;
import java...