$(xhr.responseText) 会报错, Uncaught Error: Syntax error, unrecognized expression: <!DOCTYPE html>
jquery 1.10以后需要加上parseHTML后使用
data = $.parseHTML(xhr.responseText, document, true);
var $table = $(data).find("table");
摘自http://www.myexception.cn/ruby-rails/1489191.html