Javascript-jqueryajax program Problems

{Code ...} this ajax program is no problem when I put it on the HTML page (Url: www.lanxiang.comIndexajax_load_cartNum.html), but once the URL path of the ajax request for the js file is released separately, an additional Public directory (Url: www. lanxiang...

$(function(){    $.post("{:u('Index/ajax_load_cartNum')}",function(msg)    {           var oGoodsNum = document.getElementById('cartGoodsNum');        if(msg.flag)        {            oGoodsNum.innerHTML = msg.cartGoodsNum;        }        else        {            oGoodsNum.innerHTML = 0;        }        },'json')});

This ajax program I put on the HTML page is okay (Url: http://www.lanxiang.com/Index/ajax_load_cartNum.html ),
However, once the js file is released separately
The URL path of the ajax request will come out with a Public directory (Url: http://www.lanxiang.com/Public/%7B:u ('index/ajax_load_cartNum ') % 7D), the page contains this label

Reply content:

$(function(){    $.post("{:u('Index/ajax_load_cartNum')}",function(msg)    {           var oGoodsNum = document.getElementById('cartGoodsNum');        if(msg.flag)        {            oGoodsNum.innerHTML = msg.cartGoodsNum;        }        else        {            oGoodsNum.innerHTML = 0;        }        },'json')});

This ajax program I put on the HTML page is okay (Url: http://www.lanxiang.com/Index/ajax_load_cartNum.html ),
However, once the js file is released separately
The URL path of the ajax request will come out with a Public directory (Url: http://www.lanxiang.com/Public/%7B:u ('index/ajax_load_cartNum ') % 7D), the page contains this label

Personal guesses,{:u}Tag fromphpFile is not parsed.

Programming Problems + js files cannot parse php and can only be stored in php
DecodeURI ("http://www.lanxiang.com/Public/%7B:u ('index/ajax_load_cartNum ') % 7D ")
"Http://www.lanxiang.com/Public/{:u ('index/ajax_load_cartNum ')}"