<script>

        //应用

        let url = 'https://www.imooc.com/course/list?c=fe';

        // const addURLParam = (url,name,value)=>{

        //     //先判断有没有‘？’如果没有就加上？,有的话加上&

        //     url += url.includes('?')?'&':'?';

        //     //再添加名值对

        //      url += `${name}=${value}`;

        //     return url;

        // };

        //完善版本

        const addURLParam = (url,name,value)=>{

            if(url.includes('?',url.length-1)){

                url +=`${name}=${value}`;

            }else{

               if(url.includes('&',url.length-1)){

                   url += `${name}=${value}`;

               }else{

                   url += `&${name}=${value}`;

               }

            }

            return url;

        };

        url = addURLParam(url,'c','fe');

        console.log(url);

        url = addURLParam(url,'sort','pop');

        console.log(url);

  </script>