添加头文件中的xml,script,css等内容方法

function   $import(path,type,title,idname){  
          var   s,i;  
          if(type=="js"){  
                  var   ss=document.getElementsByTagName("script");  
                  for(i=0;i<ss.length;i++){  
                          if(ss[i].src   &&   ss[i].src.indexOf(path)!=-1)return   ss[i];  
                  }  
                  s=document.createElement("script");  
                  s.type="text/javascript";  
                  s.src=path;  
          }else   if(type=="css"){  
                  var   ls=document.getElementsByTagName("link");  
                  for(i=0;i<ls.length;i++){  
                          if(ls[i].href   &&   ls[i].href.indexOf(path)!=-1)return   ls[i];  
                  }  
                  s=document.createElement("link");  
                  s.rel="alternate   stylesheet";  
                  s.type="text/css";  
                  s.href=path;  
                  s.title=title;  
                  s.disabled=false;  
          }else   if(type=="xml"){  
                  var   xl=document.getElementsByTagName("xml");  
                  for(i=0;i<xl.length;i++){  
                          if(xl[i].id==idname) return   xl[i];  
                  }  
                 s=document.createElement("xml");   
                  s.id=idname;
          }     
          else   return;  
          var   head=document.getElementsByTagName("head")[0];  
          head.appendChild(s); 
          return   s;  
  }