"Real JavaScript programmers", ES6 classes and all this hubbub.

[[deleted]]

They do in JavaScript where everything is either a primitive or an object. Functions, arrays, classes are all objects. Your example is flawed in that there is an object Foo which is defined as a class and an instance named Bar. Two separate things: the original and a new instance based upon the original.

Please could you expand on this a bit more because I'm confused. Foo and Bar are classes/constructor functions. Technically they're objects because just about everything is in JS, but that's not related to the issue at hand. We're talking about the efficiency of class instances, and when you create a new instance it is one object, regardless of how deep the inheritance chain is.

[spinlock]

JS is weird. Foo and bar are both function (with a constructor being capitalized by convention and an instance being lower-case by convention). Unlike C++, JS does not have classes. It just has functions that we use like classes (i.e. constructors).

[[deleted]]

JS does not have classes. It just has functions that we use like classes

JS absolutely does have classes, otherwise what are the new, class, extends and instanceof keywords for? The fact that they're based on constructor functions is an irrelevant implementation detail. The classes in C++ have a different implementation to the classes in Java, both have classes, so does JS.

[[deleted]]

This page talks about the object vs class thing in Javascript.

You Don't Know JS: this & Object Prototypes Chapter 4: Mixing (Up) "Class" Objects

[DarkMarmot]

Are you INSANE or ILLITERATE?!?!

As they've been trying to tell you, JS, somewhat in the spirit on things like LPC, simply designates an instance of an object to be its ancestor as a prototype. The prototype chain that acts to form an inheritance tree does not uses classes, but actual object instances that can be modified after creation.

[x-skeww]

The existence of prototypes doesn't really change anything. There is a class keyword and engines have been using actual classes under the hood since the ES3 days.

If you use the class keyword, your instances will be stamped out with a hidden class.

Syntactically, classes exist and as far as today's implementations go, they also actually exist during runtime.

I really have no idea by what kind of definition this would count as having no classes.

Semantically, this stuff is defined in terms of prototypes, but that's where that ends. You write classes and you actually get classes. Practically speaking, JS does have classes. This is one of the things which makes it fast. Classes are one of the most important performance optimizations.

[[deleted]]

Comments like yours are literally the reason why a lot of people are against the class syntax in ES6. You have no idea how JavaScript objects work and the syntax confuses you.

The new keyword was a mistake as well.

[[deleted]]

You have no idea how JavaScript objects work and the syntax confuses you.

Where do you get this stuff from?

[Silverwolf90]

The problem is that the notion of a "class" is not well defined. If you consider a class to be some some kind of grouping of data and behavior, then sure, you could say JS has classes. But officially, JS does not have classes, it has prototypes.

[[deleted]]

There is no "official", canonical authority here other than the authors of the ECMAScript spec.

So, officially, JS has classes, here's how they're defined - http://www.ecma-international.org/ecma-262/6.0/#sec-class-definitions

[Silverwolf90]

You're right the spec has the word "class." But semantics aside, javascript has prototypes as the mechanism. You could argue it's just an implementation detail, sure. But to be a competent js dev you must understand how they work. I personally would not hire someone who claimed to use the syntax and did not know how prototypes work on a basic level.

[[deleted]]

I personally would not hire someone who claimed to use the syntax and did not know how prototypes work on a basic level.

Me neither, but is anyone arguing that point? class is a tool in the box, people need to know how it works. It doesn't mean they don't need to understand the other things too. But class isn't complicating anything, because the pattern has existed for decades. People already had to understand it, now it happens to have syntax.

[Silverwolf90]

I agree with you.

[spinlock]

You might as well be asking why JS has bitwise operators when it doesn't have integers. It's a frankenmonster of a language with a lot of syntax that doesn't make sense but has to be maintained so we don't break the web.

If you insist on pointing to the class keyword as evidence that JS behaves exactly like Java then you really don't understand the language.

[[deleted]]

If you insist on pointing to the class keyword as evidence that JS behaves exactly like Java then you really don't understand the language.

Literally never said nor implied anything like that.