如何在JavaScript中调用静态子类方法

Question

How can I call a static method of a subclass from a static method of the parent class?

class A {

  static foo(){
    // call subclass static method bar()
  }
}

class B extends A {

  static bar(){
    // do something
  }
}

B.foo()

Update :

The reason why I tried this is that subclasses of A would have worked best as singletons in my context and I wanted to use the template method pattern in A.

Since it looks like I cannot get a reference to a subclass from a static context I am now exporting instances of subclasses of A which works just as well. Thanks.

Update 2

Yes, it is a duplicate to a degree (the other question does not involve subclassing). The reference, even from a static context, is this . So this works:

static foo(){
    this.bar();
}

Answer 1

I am a bit confused to your need, as it seems you sorta already get what you need to do with B.foo(). So, is this what you need?

class A {

  static foo(){
    // call subclass static method bar()
    // Because it is "static" you reference it by just calling it via
    // the class w/o instantiating it.
    B.bar() 

  }
}

class B extends A {

  static bar(){
    // do something
    console.log("I am a static method being called")
  }
}

// because "foo" is static you can call it directly off of 
// the class, like you are doing
B.foo()

// or
var D = new B()
D.bar() // won't work ERROR
A.foo() // Works <-- Is this is specifically what you are asking? Or 
        // calling it in the Super class like B.bar(), that is done in static method foo?

Is this what you are asking? If this does not answer your question, please let me know what I am misunderstanding and I'll try to answer. Thanks.

Answer 2

It makes the template pattern somewhat less elegant, but you can accomplish this via super in the subclass, eg:

class A {
  static foo() {
    this.bar()
  }
}

class B extends A {
  static foo() {
    super.foo()
  }
  static bar() {
    console.log("Hello from B")
  }
}

B.foo()