已废弃 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This feature is obsolete.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__` 属性曾经用来存放对象的可枚举的属性的个数，但是已经被废除。

## 语法

    obj.__count__

## 示例

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

## 详细说明

无需详细说明

## 浏览器兼容性

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

- Desktop
- Mobile

Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari
--- | --- | --- | --- | --- | ---
Basic support | 未实现 | 未实现 | 未实现 | 未实现 | 未实现

Feature | Android | Chrome for Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile
--- | --- | --- | --- | --- | --- | ---
Basic support | 未实现 | 未实现 | 未实现 | 未实现 | 未实现 | 未实现

## 更多请参看

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