mobx - decorator with track changes.ts

function observable(target: any, propertyKey: string): PropertyDecorator {
  return {
    get(): any {
      return this._value;
    },
    set(value: any) {
      console.log(`Gotcha! value is ${value}.`);
      this._value = value;
    },
  };
}

class State {
  @observable foo;
}

const state1 = new State();
const state2 = new State();

state1.foo = 42; // set() is called
state2.foo = 73; // set() is called
console.log(state1.foo); // get() is called
console.log(state2.foo); // get() is called