HTMLObjectElement：validationMessage 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 December 2018.
HTMLObjectElement 接口的 validationMessage 只读属性返回一个表示描述控件不满足的验证约束（如果有的话）的本地化消息字符串。如果控件不是约束验证（willValidate 是 false）的候选者，或者它满足其约束，则此字符串为空。
值
一个字符串。
规范
| Specification |
|---|
| HTML Standard # dom-cva-validationmessage-dev |
浏览器兼容性
BCD tables only load in the browser