在此页

• 句法
• 范例
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

非标
此特征是非标准的，且不在标准轨道中。不要在面向 Web 的生产站点中使用它：它不适用于每个用户。实现之间可能存在大的不兼容性，且行为将来可能改变。

Obsolete since Gecko 2 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1)
This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

__count__ property used to store the count of enumerable properties on the object, but it has been removed.

句法

obj.__count__
					

范例

{ 1: 1 }.__count__              // 1
[].__count__                    // 0
[1].__count__                   // 1
[1, /* hole */, 2, 3].__count__ // 3
					

规范

Not part of any standard.

浏览器兼容性

Not supported anywhere. Historically supported until Firefox 4.

另请参阅

• [Blog post] More changes coming to SpiderMonkey: the magical __count__ property is being removed

元数据

• 最后修改： Apr 28, 2020

相关话题

1. 标准内置对象
2. Archive
3. 继承：
4. Function
5. 特性
   1. Function.arguments
   2. Function.caller
   3. Function.displayName
   4. Function.length
   5. Function.name
6. 方法
   1. Function.prototype.apply()
   2. Function.prototype.bind()
   3. Function.prototype.call()
   4. Function.prototype.toSource()
   5. Function.prototype.toString()
7. Object
8. 特性
   1. Object.prototype.__count__
   2. Object.prototype.__noSuchMethod__
   3. Object.prototype.__parent__
   4. Object.prototype.__proto__
   5. Object.prototype.constructor
9. 方法
   1. Object.prototype.__defineGetter__()
   2. Object.prototype.__defineSetter__()
   3. Object.prototype.__lookupGetter__()
   4. Object.prototype.__lookupSetter__()
   5. Object.prototype.hasOwnProperty()
   6. Object.prototype.isPrototypeOf()
   7. Object.prototype.propertyIsEnumerable()
   8. Object.prototype.toLocaleString()
   9. Object.prototype.toSource()
   10. Object.prototype.toString()
   11. Object.prototype.unwatch()
   12. Object.prototype.valueOf()
   13. Object.prototype.watch()
   14. Object.setPrototypeOf()