How to instantiate different functions given as parameter in short

Question

I have many classes and for each class, methods to initialize an instance:

function A() {}
function B() {}

function a(arg) {
  return new A(arg);
}

function b(arg) {
  return new B(arg);
}

I want to have a single function to initialize one of these classes like this:

function any(AorB) {
  return new AorB();
}

How can I do that so the overall code size is small?

Like this? https://stackoverflow.com/a/28244500/1762224 – Mr. Polywhirl Aug 25 '20 at 16:30 — Mr. Polywhirl, Aug 25 '20 at 16:30

score 1 · Answer 1 · answered Aug 25 '20 at 16:39

If the A and B "classes" are defined at the window-level, you can call the constructor dynamically.

console.log(any('B').name); // '$B'

function A() { this.name = '$A' }
function B() { this.name = '$B' }

function any(AorB) {
  return constructorApply(window[AorB]);
}

function constructorApply(ctor, args) {
  return new (ctor.bind.apply(ctor, [null].concat(args)))();
};

How to instantiate different functions given as parameter in short

1 Answers1