如何获取Office UI Fabric SpinButton的值

<div class="ms-SpinButton">
  <input type="text" id="mySpinButton" class="ms-TextField-field" />
  <div class="ms-SpinButton-container">
    <button class="ms-Button ms-Button--icon ms-Button--increment">
      <i class="ms-Icon ms-Icon--ChevronUpSmall"></i>
    </button>
    <button class="ms-Button ms-Button--icon ms-Button--decrement">
      <i class="ms-Icon ms-Icon--ChevronDownSmall"></i>
    </button>
  </div>
</div>

var spinButton = document.getElementById('mySpinButton');
spinButton.addEventListener('input', function() {
  var value = spinButton.value;
  console.log('SpinButton的值为：' + value);
});