mobx.js

class SomeClass {
  @observable prop1;
  @observable prop2;
  
  @action init(prop1, prop2) {
    this.setProp1(prop1); // or this.prop1 = prop1; ?
    this.setProp2(prop2); // or this.prop2 = prop2; ?
  }
  
  @action
  setProp1(value) {
    this.prop1 = value;
  }
  
  @action
  setProp2(value) {
    this.prop2 = value;
  }
}