Function trackValueOnNode

docs/external/js/react-dom.development.js:1836–1880

(node)

  }

  function trackValueOnNode(node) {
    var valueField = isCheckable(node) ? 'checked' : 'value';
    var descriptor = Object.getOwnPropertyDescriptor(node.constructor.prototype, valueField);
    var currentValue = '' + node[valueField]; // if someone has already defined a value or Safari, then bail
    // and don't track value will cause over reporting of changes,
    // but it's better then a hard failure
    // (needed for certain tests that spyOn input values and Safari)

    if (node.hasOwnProperty(valueField) || typeof descriptor === 'undefined' || typeof descriptor.get !== 'function' || typeof descriptor.set !== 'function') {
      return;
    }

    var get = descriptor.get,
        set = descriptor.set;
    Object.defineProperty(node, valueField, {
      configurable: true,
      get: function () {
        return get.call(this);
      },
      set: function (value) {
        currentValue = '' + value;
        set.call(this, value);
      }
    }); // We could've passed this the first time
    // but it triggers a bug in IE11 and Edge 14/15.
    // Calling defineProperty() again should be equivalent.
    // https://github.com/facebook/react/issues/11768

    Object.defineProperty(node, valueField, {
      enumerable: descriptor.enumerable
    });
    var tracker = {
      getValue: function () {
        return currentValue;
      },
      setValue: function (value) {
        currentValue = '' + value;
      },
      stopTracking: function () {
        detachTracker(node);
        delete node[valueField];
      }
    };
    return tracker;
  }

  function track(node) {
    if (getTracker(node)) {