Browsers are designed for the so-called event-driven model. In this model, code isn't executing continuously. It waits for user events, like button presses, mouse clicks, or scrolling.
Each of these events and dozens of others triggers the necessary handler. Every handler has special requirements: it shouldn't stop anything, because one event can cause many things almost in parallel. In other words, the user should be able to continue interacting with the interface.
Asynchronous code is wholly different from synchronous code and takes time to get used to it. It has a different way of handling errors and a different approach to writing code. Adding some features creates problems in other places: what was easy to do in synchronous code may be difficult in asynchronous code. It is the price we pay for performance.
These approaches are important in their way, and we will discuss them in this course. In the end, you'll learn how to write modern, efficient, and understandable code with the advantages of asynchronous code. It will be almost as good as synchronous code in terms of clarity and simplicity.
The main topics of this course are:
You can find the correct sequence of courses in the profession Frontend Programmer.
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