摘要：
```javascript
function versions(){ let u = window.navigator.userAgent return { trident: u.indexOf('Trident') > -1, //IE内核 presto: u.indexOf('Presto') > -1, //opera内核 we... 阅读全文
摘要：
<!--[if !IE]><!--> 除IE外都可识别 <!--<![endif]--> 项目范例说明![if !IE]The NOT operator. This is placed immediately in front of the feature, operator, or subexpr 阅读全文