向上干燥-如果不存在实例，则调用类方法，否则调用实例方法

Question

Situation

If input is a "start", automatically calculate the "end" and then prefill the page with the "end"

If input is a "end", simply prefill the page with it

I'm trying to write a class to handle this functionality.

class EndVal(start_value) {
  constructor() {
    this.end_value = start_value + 10
    $("#end").text(this.end_value)
  }

  static prefill(end_value) {
    $("#end").text(end_value)
  }
}

Based on the above code if what you have is a "start", you'd just do new EndVal(start_value) , but if you already have an "end" rather than instantiating a new object, you can just do EndVal.prefill(end_value) . But it isn't very DRY... I'm wondering how to fix it, and somehow link the instance and class methods?

Answer 1

The prefill method should use the passed argument instead of this . Now you can all the method from the constructor:

 class EndVal { constructor(start_value) { this.end_value = start_value + 10 this.constructor.prefill(this.end_value); } static prefill(end_value) { console.log(end_value); } } const endVal = new EndVal(15); EndVal.prefill(28);