Unobtrusive Javascript

1. Unobtrusive Javascript有三层含义：一是在HTML代码中不会随意的插入Javsscript代码，只在标签中加一些额外的属性值，然后被引用的脚本文件识 别和处理；二是通过脚本文件所增加的功能是一种渐进式的增强，当客户端不支持或禁用了Javsscript时网页所提供的功能仍然能够实现，只是用户体验 会降低；三是能够兼容不同的浏览器。
2. 可以看到魔力就在于以data-ajax开头的一些属性中，当Javascript被禁用后，表单仍能提交，链接也能点开，只不过不再是异步的了。
3. Built-in validator controls have been configured to use unobtrusive JavaScript for client-side validation logic. This significantly reduces the amount of JavaScript rendered inline in the page markup and reduces the overall page size. Unobtrusive validation is added globally to the ASP.NET Web Forms Application template based on the setting in the <appSettings> element of the Web.config file at the root of the application.