cache (default: true, false for dataType 'script' and 'jsonp') Type: Boolean
If set to false, it will force requested pages not to be cached by the browser. Note: Setting cache to false will only work correctly with HEAD and GET requests. It works by appending "_={timestamp}" to the GET parameters. The parameter is not needed for other types of requests, except in IE8 when a POST is made to a URL that has already been requested by a GET.
对于type为 'script' 和 'jsonp'的请求,jQuery 会附带这一个参数来阻止浏览器缓存
http://api.jquery.com/jquery.ajax/
If set to false, it will force requested pages not to be cached by the browser. Note: Setting cache to false will only work correctly with HEAD and GET requests. It works by appending "_={timestamp}" to the GET parameters. The parameter is not needed for other types of requests, except in IE8 when a POST is made to a URL that has already been requested by a GET.
如果你不想要这个参数,设置 cache: true