Why no overloaded constructor implementations in TypeScript?

Question

In TypeScript it's only possible to overload the constructor type signatures, but not the Implementation. Is there and reason behind this? Overloading constructors like in Java are really useful I think. For example a definition for vectors could be the end cordinates, or start and endpoint or two vectors and so on. The current approach in TypeScript is very chaotic. So why doesn't typescript have it?

Answer 1

Yes, there's a reason for it, and the reason is that javascript does not support using the same name for a method or a member.

Consider the following typescript:

class MyClass {
    myMethod() {}
    myMethod(str: string) {}
}

The compiled version is:

var MyClass = (function () {
    function MyClass() {
    }
    MyClass.prototype.myMethod = function () { };
    MyClass.prototype.myMethod = function (str) { };
    return MyClass;
}());

As you can see, the 2nd implementation of myMethod is replacing the first implementation.
Because of that you can only overload the signatures and then you need to provide a single implementation which satisfies all of the declared signatures.