July 2020
Intermediate to advanced
608 pages
15h 43m
English
Content preview from JavaScript
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4Classes
In this chapter you'll learn how
class syntax works for creating JavaScript constructors and associated prototype objects. We'll compare and contrast the new syntax with the old, highlight that it's still the same prototypical inheritance JavaScript is famous for, and explore how powerful and simple the new syntax is. You'll see how to create subclasses, including subclasses of built-ins (even ones that can't be subclassed in ES5 and earlier like
Array and
Error), how
super works, and what
new.target is for and how to use it.
This chapter doesn't cover features that are coming in ES2020 or ES2021 like public class fields, private class fields, and private methods. See Chapter 18 for coverage of those.
WHAT IS A CLASS?
Before looking at the new syntax, let's address the elephant in the room: JavaScript doesn't really have classes, does it? It just emulates them with prototypes, right?
That's a popular perspective, because people confuse ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.