HTMLObjectElement：contentDocument 属性
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since July 2015.
HTMLObjectElement 接口的 contentDocument 只读属性返回一个表示对象元素的嵌套浏览器上下文的活动文档的 Document（如果有的话），否则返回 null。
值
一个 Document。
规范
| Specification |
|---|
| HTML Standard # dom-object-contentdocument |
浏览器兼容性
BCD tables only load in the browser