无法让第二个事件监听器为MVC计数器应用工作

Question

我试图使用MVC方法创建一个简单的计数器应用程序，我还没能弄清楚为什么事件侦听器的下行计数器不工作，但上行计数器。我肯定忽略了什么，但我对这种方法完全陌生。任何帮助都将非常感激。

//model 
var model = 
      {
        clickCount: 0
      };

//controller 
  var controller = {
      init: function() { 
           view.init();
      },
      incrementCounterUp: function() {
        counter.textContent = model.clickCount += 1;
      },
      incrementCounterDown: function() {
        counter.textContent = model.clickCount -= 1;
      }
  };

//view 
var counter = document.createElement('p');
counter.textContent = (model.clickCount);
counter.id = counter;
document.body.appendChild(counter);
var upButton = document.createElement("button");
upButton.id = upButton;
document.body.appendChild(upButton);
var upButtonText = document.createTextNode("Up");
upButtonText.id = upButtonText;
upButton.appendChild(upButtonText);
var downButton = document.createElement("button");
downButton.id = downButton;
document.body.appendChild(downButton);
var downButtonText = document.createTextNode("Down");
downButtonText.id = downButtonText;
downButton.appendChild(downButtonText);

var view = {
    init: function() {
    // store pointers to our DOM elements for easy access 
      this.counterElem = document.getElementById(counter);
      this.upButtonElem = document.getElementById(upButton);
      this.upButtonElem.addEventListener('click', function(){
          controller.incrementCounterUp();
      });
      this.downButtonElem = document.getElementById(downButton);
      this.downButtonElem.addEventListener('click', function(){
          controller.incrementCounterDown();
      });
    }
};

controller.init();

Answer 1

contoller.incrementCounterDown();

你拼错了controller。: P

Answer 2

 //model 
var model = 
      {
        clickCount: 0
      };

//controller 
  var controller = {
      init: function() { 
           view.init();
      },
      incrementCounterUp: function() {
        model.clickCount += 1
        view.render()
      },
      incrementCounterDown: function() {
        model.clickCount -= 1
        view.render()
      }
  };

//view 
var counter = document.createElement('p');
counter.textContent = (model.clickCount);
counter.id = 'counter';
document.body.appendChild(counter);
var upButton = document.createElement("button");
upButton.textContent = 'Up'
upButton.id = 'upButton';
document.body.appendChild(upButton);
var downButton = document.createElement("button");
downButton.textContent = 'Down';
downButton.id = 'downButton';
document.body.appendChild(downButton);

var view = {
    init: function() {
    // store pointers to our DOM elements for easy access 
      this.upButtonElem = document.getElementById('upButton')
      this.downButtonElem = document.getElementById('downButton')
      this.downButtonElem.addEventListener('click', function(){
          controller.incrementCounterDown()
      })
      this.upButtonElem.addEventListener('click', function(){
          controller.incrementCounterUp()
      })
    },
    render: function() {
      this.counterElem = document.getElementById('counter')
      this.counterElem.textContent = model.clickCount
    }
};


controller.init();