title: three.js load multiple objects asynchronous issue
body: <p>am loading multiple models on the same time to a scene, but it fails to load all the models, it only loading one model on the scene</p>
  
  <p>For example am having a building scene with the multiple objects like chairs, toys and so on inside that building, while loading those objects the only one object is loading, but somehow if i do a alert on end of the function all the models are loading </p>
  
  <p><img src="https://i.stack.imgur.com/p3COj.png" alt="Example 1 what am getting now"></p>
  
  <p><img src="https://i.stack.imgur.com/eemyo.png" alt="Example 2 what i want"></p>
  
  <p>Image1 what am getting now, Image2 what actually i want </p>
  
  <p>my code is follows</p>
  
  <pre><code>function load_file(floor_number,x,y,z,width,height,rotation,angle,file)
  {       
  obj_x=x;
  obj_y=y;
  obj_z=z;
  obj_width=width;
  obj_height=height;
  obj_rotation=rotation;
  var object_material = new THREE.MeshBasicMaterial({                 
            color: 0xd6d6d6,  
            traansparent : true,
            opacity   : -2.5,
            side: THREE.DoubleSide            
        });       
  var   loader = new THREE.JSONLoader();      
  loader.load("uploads/accessories/3d/code/3dfile_"+file+".js",
            function(geometry, object_material) 
            {
  
                var object = new THREE.Mesh(geometry, new THREE.MeshFaceMaterial(object_material));
                console.log(object);
                model = new THREE.Object3D();
  
                model.add(object);    
                model.position.set(obj_x,obj_y,obj_z);        
                model.scale.set(obj_width,obj_height,obj_rotation);   
                model.opacity =2;
                model.rotation.y = 600; 
                model.duration = 12000;
                model.mirroredLoop = true;
                model.castShadow = true;
                model.receiveShadow = true;
                scene.add(model);                         
            }
        );        
  
       // alert('hi'); if i remove this comment second model is loading perfectly
  return true;                    
  }
  </code></pre>
  
  <p>also tried to load the object's by id using <code>Object3D.getObjectById()</code> this is also fails
  i know this is about the asynchronous problem, but i can't get ride of this, any help on this?</p>