Is it possible to call an instance method from a static method of a class?

Question

It's easy to build instance methods that call on the polymorphic static method:

class MyClass {
  instanceMethod() {
    this.constructor.staticMethod();
  }
  static staticMethod() {
    console.log('first');
  }
}

class OtherClass extends MyClass {
  static staticMethod() {
    console.log('second');
  }
}
const i = new OtherClass();
i.instanceMethod();

However, I want to do the opposite - define a static method that calls upon the polymorphic instance method - sending this as a parameter.

class MyClass {
  instanceMethod() {
    console.log('first');
    this.constructor.staticMethod();
  }
  static staticMethod(self) {
     // how to call??
     instancefromstatic(this).instanceMethod.call(self);
  }
}

class OtherClass extends MyClass {
  instanceMethod() {
    console.log('second');
  }
}
OtherClass.staticMethod({});

Answer 1

If I understand you are after…

When you call OtherClass.staticMethod() , this will be the OtherClass . So if you want to access the instance method, you will find it on the this.prototype .

 class MyClass { instanceMethod() { console.log('first'); this.constructor.staticMethod(); } static staticMethod(self) { this.prototype.instanceMethod() return this.prototype.testVal } } class OtherClass extends MyClass { instanceMethod() { console.log('second'); } get testVal(){ console.log("getting") return "test value" } } // logs 'second': console.log(OtherClass.staticMethod({})); 

Be careful in the MyClass instanceMethod , because you can create an infinite loop the way you have it setup if you call MyClass.staticMethod()

Answer 2

Instance is merely a context of a method call in this case. You are almost getting there. Passing in self to the staticMethod. And then you can call it via class name.

MyClass.instanceMethod.call(self)