javascript - 无法枚举 getter/setter 属性

Question

我正在编写一些反射代码以尝试删除属性和函数，但我似乎根本无法获得 getter/setter。

我对属性的反射代码是:

Reflector = function() { };

Reflector.getProperties = function(obj) {
  var properties = [];
  var proto = obj;
  while (proto != Object.prototype) {
    console.log('Scrapping proto: ', proto);
    for (var prop in proto) {
      console.log('typeof ' + prop + ": ", typeof obj[prop]);
      if (typeof obj[prop] != 'function') {
        properties.push(prop);
      }
    }
    proto = Object.getPrototypeOf(proto);
  }
  return properties;
};

它运行的示例(带有我的调试消息)是:

var SimpleTestObject = function() {
  this.value = "Test1";
  this._hiddenVal = "Test2";
  this._readOnlyVal = "Test3";
  this._rwVal = "Test4";
};
SimpleTestObject.prototype = {
  get readOnlyVal() {
    return this._readOnlyVal;
  },
  get rwVal() {
    return this._rwVal;
  },
  set rwVal(value) {
    this._rwVal = value;
  },
  func1: function() {
    // Test
  }
};
SimpleTestObject.func2 = function(test) { /* Test */ };
SimpleTestObject.outsideVal = "Test5";

var props = Reflector.getProperties(SimpleTestObject);
console.log('props: ', props);
console.log('Object.getOwnPropertyNames: ', Object.getOwnPropertyNames(SimpleTestObject));
console.log('rwVal property descriptor: ', Object.getOwnPropertyDescriptor(SimpleTestObject, 'rwVal'));
console.log('rwVal (2) property descriptor: ', Object.getOwnPropertyDescriptor(Object.getPrototypeOf(SimpleTestObject), 'rwVal'));

我希望看到的输出到我的Reflection.getProperties(SimpleTestObject)是 ['readOnlyVal', 'rwVal', 'outsideVal'] ，但我只看到 outsideVal .此外，当我尝试使用 getOwnPropertyDescriptor()看看 rwVal是可枚举的，它返回为未定义。因此，考虑到它可能以某种方式显示在上面的原型(prototype)中，我尝试提升一个级别，但仍然未定义。

Answer 1

要枚举 getter，请在原型(prototype)上使用 Object.keys 或 Object.getOwnPropertiesNames 而不是构造函数或/和实例:

function readGetters(obj) {
    var result = [];
    Object.keys(obj).forEach((property) => {
        var descriptor = Object.getOwnPropertyDescriptor(obj, property);
        if (typeof descriptor.get === 'function') {
            result.push(property);
        }
    });
    return result;
}



var SimpleTestObject = function() {
    this.value = "Test1";
    this._hiddenVal = "Test2";
    this._readOnlyVal = "Test3";
    this._rwVal = "Test4";
};
SimpleTestObject.prototype = {
    get readOnlyVal() {
        return this._readOnlyVal;
    },
    get rwVal() {
        return this._rwVal;
    },
    set rwVal(value) {
        this._rwVal = value;
    },
    func1: function() {

    }
};
SimpleTestObject.func2 = function(test) { /* Test */ };
SimpleTestObject.outsideVal = "Test5";


// For constructor
console.log(readGetters(SimpleTestObject.prototype));

// For instance
var instance = new SimpleTestObject();
console.log(readGetters(Object.getPrototypeOf(instance)));