code: function preload(node) {
          var self = arguments.callee;
          if (node && node.nodeType === 1) {
              var $preload = $('preload', node),
                  len = $preload.length;
              while (len--) {
                  var tmpNode = $preload[len],
                      dataset = tmpNode.dataset,
                      type = dataset.type,
                      url = dataset.url;
                  var fn = preloadFn['load' + type.toUpperCase()];
                  typeof fn === 'function' && fn(url, function(tmpNode) {
                      return function() {
                          //将该标签删除，释放内存
                          tmpNode.parentNode && tmpNode.parentNode.removeChild(tmpNode);
                          tmpNode = null;
                      };
                  }(tmpNode));
              }
          }
          return self;
      }
docs: 预加载资源 <preload data-type="js||css" data-url="">