我有一个 .VAL（）解决方法解决它：

I have solved it with a .val() workaround:

   var ranger = element.find("input");
   ranger.bind("change",function(){

      // console.log("changed! ", scope.zoom_level) // Not working

      scope.$apply(function(){
           scope.zoom_level = ranger.val();
      });
      console.log("changed! ", scope.zoom_level) // Now it does
   });

例如： http://jsfiddle.net/hRDVS/