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Using JavaScript classes without the `class` keyword

Corbin Crutchley on June 29, 2023

Classes in JavaScript are both powerful and weird. While they allow us to create named objects with similarly purposed methods and properties, they...
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Eckehard •

People are used to use all kind of "tricks" in Javascript.

    const sqr = (x) => x*x
    console.log(sqr(3))
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Everybody knows, this defines a function, but WHY do we use a language, that states to define a constant, but creates a function instead? Why does a language allow to use this kind of ambiguity?

There are a lot of good reasons, why things are a bit wiered in JS, but not everybody is happy to use a language like a shell game. Classes make Javascript more explicit. If you define a class using the CLASS-keyword, everybody will know your intention. This is often not the case with common Javascript code...

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Corbin Crutchley •

I mean, I'm on board with the class keyword. This wasn't a slam piece, it was to help folks understand historical context of the language and maybe even understand the prototype system better

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Eckehard •

Of course, thank you very much for your effort. I just wanted to note, that it is not a advantage to define a class without using the keyword. Even if it was only "syntactical shugar" (which i think it is not), it is better to use a clear naming for things you do.

We should always be clear that a programming language is made for programmers, not for computers. A computer uses opcodes, so in that case we should use assembler.

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Vladas Saulis •

IMO computer languages are made for computers, - not for programmers. When you start realize it, programming will make easier.

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Eckehard •

Sy, why do we not use assembler? It is much easier to understand for a computer...

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Vladas Saulis •

Mostly we use heavy-weight frameworks which finally generate assembler/machine code for computers, not for you.

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Calin Baenen •

And the post did a great job illustrating that.

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JoelBonetR 🥇 • • Edited

I'm inclined to think that the code example along the comment on the following paragraph is due to a common misunderstanding after seeing dozens of posts like "Do you prefer const or function?" because the only good answer to this is "it doesn't matter", let me explain why:

You can do:

const square = (x) => x*x;
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or

function square (x) { return x*x; }
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But they are not the same, technically.

1- const prevents reassignment of the reference (name) while function does not.
2- An arrow function doesn't have it's own lexical context, so it won't have a scoped this and can't be used as a constructor while function can be.
3- A const arrow function needs to be declared before calling it, otherwise it's undefined
4- A function can be declared after calling it.

Please note that you can also do:

const square = function(x) { return x*x; }
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Which both prevents reassignment and creates a lexical context, so it's (or it should be) a matter of -technical- needs on a given point on your software rather than a personal preference.

Now, as we should code for other humans to understand it, rather than just "the machine", the key here is in the naming guidelines, as a rule of thumb:

const myDog =
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No verb, this should be a value.

const getUserById =
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Does it have a verb? Yes, it should be a function then!

and please, no abbreviations nor acronyms on variable/const/function/class names please! 😂

Hope it helps,

Best wishes 😁

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Vladas Saulis •

There is no such primitive like 'class' in JS.

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Eckehard •

?

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Vladas Saulis •

There are predefined primitives in JS. And there is no primitive 'class'.

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Vladas Saulis •

Use 'var' - it's clearer.

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Vladas Saulis • • Edited

I always knew that classes in JS are just syntactic sugar.

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Uriel dos Santos Souza •

No!

Andrea Giammarchi

JS classes are not “just syntactic sugar” | by Andrea Giammarchi | Medium

Andrea Giammarchi ・ ・
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bhagatparwinder

Classes, Not Just Syntactic Sugar

Parwinder 👨🏻‍💻 ・ Sep 4 '20 ・ 3 min read

#javascript #beginners #codenewbie #webdev
Arun Rajeevan

Class is not just a Syntactic sugar in Javascript | by Arun Rajeevan | Medium

Arun Rajeevan ・ ・
Medium Logo arunrajeevan.Medium

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Vladas Saulis •

I always convert JS classes into prototype chains without any consequences.

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went • • Edited

Please fix the error of re-assigning Corbin.prototype, instead of :

Corbin.prototype = Object.create(Person.prototype);
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much better do the following:

Object.setPrototypeOf(Corbin.prototype, Object.create(Person.prototype))
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Because otherwise Corbin instance is not a member of Corbin constructor if you will use instanceof for check...

Seems there is a non-enumerable .constructor property in Corbin.prototype, accordingly with the specification, which is then used for matching instanceof. And when you just re-assign ... you deleting it.

And for sure instead of code above you may also go like this:


function Person() {
}
Person.prototype.personality = "quirky";

function Corbin() {
}
Corbin.prototype = Object.create(Person.prototype, {
    constructor: { value: Corbin },
    name: { value: "Corbin" }
});

const corbin = new Corbin;
console.log(corbin instanceof Person); // true
console.log(corbin instanceof Corbin); // true
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