why is class a reserved word in JavaScript?

Question

I am planning to implement class inherit interface using JavaScript. class is the perfect word as the name of the constructor.

class = function (classname) {}; // create a class with classname classA = new class("classA"); // create a class named classA 

Unfortunately, class is a reserved word in JavaScript.

Why does JavaScript reserve the word class (since it never uses it)?

Answer 1

It's reserved to future-proof ECMAScript

The following words are used as keywords in proposed extensions and are therefore reserved to allow for the possibility of future adoption of those extensions.

Don't fret though, if you're using best-practices in your JavaScripts, you're placing all accessible functions/variables/constructors in a namespace, which will allow you to use whatever name you'd like:

foo = {}; foo['class'] = function(){...code...}; var myClass = new foo['class'](); 

Answer 2

Languages evolve. It is prudent to reserve a few keywords that might come in use later. According to the ECMA standard, class is a Future Reserved Word.

If you did not reserve them, introducing new keywords could conflict with existing code (which already might be using the word for other things). Happened with Java and assert.