backbone.js history 里的 pushState 究竟是什么含义？

Question

pushState support exists on a purely opt-in basis in Backbone. Older browsers that don't support pushState will continue to use hash-based URL fragments, and if a hash URL is visited by a pushState-capable browser, it will be transparently upgraded to the true URL. Note that using real URLs requires your web server to be able to correctly render those pages, so back-end changes are required as well. For example, if you have a route of /documents/100, your web server must be able to serve that page, if the browser visits that URL directly. For full search-engine crawlability, it's best to have the server generate the complete HTML for the page ... but if it's a web application, just rendering the same content you would have for the root URL, and filling in the rest with Backbone Views and JavaScript works fine.

看不太懂这一段，能举一个例子吗？

Answer 1

Backbone 的路由, 通过监听网址变化来起作用.. 这个题主先要了解.
还有要了解到, 其实有两种网址 /path /#path.. 这两个什么区别.

旧的浏览器不支持其中一种, 因此 Backbone 提供了 pushState 的选项.
关键词: HTML5 History API

Answer 2

自问自答一下吧，之前旧的浏览器只能通过hashchange来判断单页app地址的变化，而由于html5 history api的出现，允许通过/path 这样的模式来渲染页面，这种模式就叫做pushState，pushState设为true意味可以采用这种模式。在backbone里面，会判断浏览器对history api的支持，不支持的浏览器自动降格为hashchange的方式来切换页面。