如何使用装饰器覆盖打字稿中类的静态方法

Question

Here is what I do in javascript

class A {
  static foo (a, b, callback) {
    setTimeout(() => {
      let result = doSomethig(a, b)
      callback(result)
    }, 1000)
  }
}

function decorator (OriginalClass) {
  return class extends OriginalClass {
    static foo (a, b) {
      return new Promise((res) => {
        super.foo(a, b, (result) => {
          res(result)
        })
      })
    }
  }
}

@decorator    
class B extends A {
}

let result = await B.foo(10, 20)

I want to overwrite a method of a class, and in the overwritten method, I want to call the original method. Is there any way to do this in Typescript?

Answer 1

You can do something like this:

class A {
  static bar() {
    console.log("barA");
  }
}

function decorator(OriginalClass: any) {

  let baseBar = OriginalClass.bar;
  OriginalClass.bar = function () {
    baseBar();
    console.log("barOverridden");
  }  
  return OriginalClass;
}

@decorator    
class B extends A {
}

B.bar();

Answer 2

function StaticMethodDecorator(
   target: Function, // the function itself and not the prototype
   propertyKey: string | symbol, // The name of the static method
   descriptor: TypedPropertyDescriptor<any>
) {
   console.log("StaticMethodDecorator called on: ", target, propertyKey, descriptor);
}

class StaticMethodDecoratorExample {
   @StaticMethodDecorator
   static staticMethod() {
   }
}

as described at: https://khru.gitbooks.io/typescript/static_method_decorator.html