在 Node/raw ES6 中，如何从父类发出事件并从其各自的构造函数触发子类中的事件？

Question

I'm currently working on exercism.io's "JS track - react project" (no not that react). The exercise is to make classes that react to one another's actions. I wasn't sure if inheritance was the best bet, but I feel like it's as close as I'm going to get. (PS This is my first post here, I tried quite a few places before deciding to ask my first question here. ('PPS') => 'Howdy' :)

`class InputCell extends EventEmitter {
  constructor(value) {
    super(value);
    this.value = value;
  }

  setValue(value) {
    this.value = value;

    // I'm assuming this emitter doesn't leave the scope of the object it creates?
    this.emit('cellChange');
  }
}

class ComputeCell extends InputCell {
  constructor(cells, compute) {
    super(cells, compute);
    this.value = compute(cells);

    // super wasn't my first choice, but 'this' didn't work either
    super.on('cellChange', () => compute(cells));
  }
}`

Edit- My apologies, here is the failing test I run.

`  test('compute cells update value when inputs are changed', () => {
    const inputCell = new InputCell(1);

    const computeCell = new ComputeCell(
      [inputCell], inputs => inputs[0].value + 1
    );

    inputCell.setValue(3);

    expect(computeCell.value).toEqual(4);
  });

`

Answer 1

@TJ Allen: I'm stuck on the same exercise, but I found the solutions page:https://exercism.io/tracks/javascript/exercises/react/solutions

it took some looking but I found this explanation to be simple enough for my understanding (specifically for the test case you posted):

export class InputCell {
  constructor(value) { // test 1: accepts input
    this.value = value;
  }

  setValue(value) {
    this.value = value; // test 2: allows input  value to be set
  }
}

export class ComputeCell {
  constructor(inputCells, func) { // test 3: allows setting compute cells
    this.inputs = inputCells;
    this.func = func;
  }

  get value() {
    return this.func(this.inputs); // test 5: compute cells update value when inputs are changed
  }
}

For other exercism.io users, note that I've left-out a comment for test 4: compute cell takes inputs in correct order as it was less relevant to the question asked here.

Edit: Personally, I think the wording of that specific test 5 case is vague and confusing.

"compute cells update value when inputs are changed"

Which inputs and where? It sounds like its asking you to some kind of event listener so that the values inside InputCell automatically trigger the values inside ComputeCell to change -- bc I thought the same.

But looking at the test, I think what they're actually asking for is: if you initialize a new instance of InputCell with a number and pass that instance as an argument to create a new instance of ComputeCell then your new ComputeCell instance will have updated its value (through the getter) based on the value of the InputCell instance you passed to it. It might have been clearer if the test message logged something this:

"compute cells return different value when called with new inputs"

still probably not as clear as I'd like, but less misleading imo.