/*** js和css按需載入 ***/
function loadJsCss(url, callback ){// 非阻塞的載入 後面的js會先執行
  var isJs = /\/.+\.js($|\?)/i.test(url) ? true : false;
  function onloaded(script, callback){//繫結載入完的回撥函式
    if(script.readyState){ //ie
      script.attachEvent('onreadystatechange', function(){
        if(script.readyState == 'loaded' || script.readyState == 'complete'){
          script.className = 'loaded';
          callback && callback.constructor === Function && callback();
        }
      });
    }else{
      script.addEventListener('load',function(){
        script.className = "loaded";
        callback && callback.constructor === Function && callback();
      }, false); 
    }
  }
  if(!isJs){ //載入css
    var links = document.getElementsByTagName('link');
    for(var i = 0; i < links.length; i++){//是否已載入
      if(links[i].href.indexOf(url)>-1){ 
        return; 
      }
    }
    var link = document.createElement('link');
    link.type = "text/css";
    link.rel = "stylesheet";
    link.href = url;
    var head = document.getElementsByTagName('head')[0]; 
    head.insertBefore(link,head.getElementsByTagName('link')[0] || null );
  }else{ //載入js
    var scripts = document.getElementsByTagName('script');
    for(var i = 0; i < scripts.length; i++){//是否已載入
      if(scripts[i].src.indexOf(url)>-1 && callback && (callback.constructor === Function) ){ 
      //已建立script
        if(scripts[i].className === 'loaded'){//已載入
          callback();
        }else{//載入中
          onloaded(scripts[i], callback);
        }
        return; 
      }
    }
    var script = document.createElement('script');
    script.type = "text/javascript";
    script.src = url; 
    document.body.appendChild(script);
    onloaded(script, callback); 
    
  }
}