Multi image uploader in Backbone.js

gistfile1.js

(function($){
  //
  //--------------------------------------   Model  :  Image
  //
  Image = Backbone.Model.extend({
    defaults: {
      'delete' : false
    }
  });
  
  
  
  //
  //--------------------------------------   Collection  :  ProductImages
  //
  ProductImages = Backbone.Collection.extend({
    model: Image,
    url: '#{ admin_product_images_path(product.id) }',
    
    allMarked: function(){
      return this.filter(function(image){ return image.get('delete'); });
    }
    
  });
  
  
  
  //
  //--------------------------------------   View  :  Image
  //
  ImageView = Backbone.View.extend({
    tagName: 'li',
    
    events: {
      'click a.img_delete'  : 'markForDestroy'
    },
    
    initialize: function(){
      this.template = ich.product_image;
      
      this.model.bind('change:delete', this.render, this);
    },
    
    render: function(){
      var self = this,
          attr = this.model.toJSON(),
          elem = $(self.el),
          marked = this.model.get('delete');
      
      if (marked) {
        attr.cssState = 'marked';
        attr.btnTitle = 'undo';
      } else {
        attr.cssState = null;
        attr.btnTitle = 'delete';
      }
      
      elem.html(
        self.template(attr)
      );
      
      // display red-tinted overlay if marked
      if (marked) {
        var img     = this.$('a.img_thumb'),
            offset  = img.offset();
        
        this.$('.img_overlay').css({
          display:  'block',
          width:    img.css('width'),
          height:   img.css('height'),
          top:      offset.top + 'px',
          left:     offset.left + 'px'
        });
      }
      return elem;
    },

    markForDestroy: function(){
      var model = this.model;
      model.set({ delete: !model.get('delete') });
      return false;
    }
  });
  
  
  
  //
  //--------------------------------------   View  :  UploaderSidebar
  //
  UploaderSidebar = Backbone.View.extend({
    className: 'span-4',
    
    events: {
      'click a.delete_imgs' : 'destroySelected'
    },
    
    initialize: function(){
      this.template = ich.multi_img_upload;
      this.collection.bind('change:delete', this.render, this);
      this.collection.bind('reset', this.render, this);
    },
    
    render: function(){
      var self = this,
          elem = $(this.el),
          collection = self.collection,
          control = self.model;
          
      elem.html(
        self.template()
      );
      
      // File uploader
      self.$('#img_drop').html5Uploader({
    		name: 'images[]',
    		postUrl: '#{ admin_product_images_path(product.id) }',
    		
    		// When the files are read by the browser
    		onClientLoad: function(){
    		  control.startLoad();
    		},
    		
    		// This is a funky callback, thanks to XmlHttpRequest.
    		onServerReadyStateChange: function(request){
    		  if (request.readyState == 4) {
    		    control.stopLoad();
    		    if (request.status == 200) {
    		      collection.reset(
    		        JSON.parse(request.responseText)
    		      )
    		    } else {
    		      throw new Error('File upload request error');
    		    }
    		  }
    		}
    	});
      
      // Delete button
      var markedCount = collection.allMarked().length;
      if (markedCount) {
        var btn = self.$('a.delete_imgs');
        btn.html('Delete selected (' + markedCount + ')');
        btn.css({ display: 'block' });
      }
      return elem;
    },

    destroySelected: function(){
      var collection  = this.collection,
          control     = this.model;
      control.startLoad();
      $.ajax({
        type: 'POST',
        url: '#{ destroy_admin_product_images_path(product.id) }',
        data: {
          images: collection.allMarked().pluck('id')
        },
        success: function(resp){
          collection.reset(resp);
          control.stopLoad();
        }
      });
      return false;
    }
    
  });
  
  
  
  //
  //--------------------------------------   View  :  ProductImages
  //
  ProductImagesView = Backbone.View.extend({
    className: 'span-16',
    
    initialize: function(){
      this.collection.bind('reset', this.render, this);
    },
    
    render: function(){
      var self = this,
          elem = $(self.el);
      
      // Clear the element and insert the new product <ul>
      elem.html('').append(
        $('<ul class="product_images">')
      );
      
      // Append image_views to product_images <ul>
      self.collection.each(function(image){
        self.$('ul.product_images').append(
          new ImageView({ model: image }).render()
        );
      });
      return elem;
    }
    
  });
  
  
  
  //
  //--------------------------------------   View  :  ImageUploader (main view)
  //
  UploaderControl = Backbone.Model.extend({
  
    defaults: {
      loadState: false
    },
    
    startLoad: function(){ return this.set({ loadState: true }); },
    stopLoad: function(){ return this.set({ loadState: false }); }
  
  });
  
  
  
  //
  //--------------------------------------   View  :  ImageUploader (main view)
  //
  ImageUploader = Backbone.View.extend({
    
    initialize: function(selector){
      var control     = this.model = new UploaderControl(),
          images      = new ProductImages(#{ @images.to_json }),
          imagesView  = new ProductImagesView({ collection: images }),
          sidebar     = new UploaderSidebar({ collection: images, model: control }),
          elem        = $(selector);
      
      // Insert views
      elem
        .append(sidebar.render())
        .append(imagesView.render());
        
      // Bind loader
      loader = $('<div class="mask_loader">');
      elem.append(loader);
      control.bind('change:loadState', function(){
        if (control.get('loadState'))
          loader.css({
            display: 'block',
            height: elem.height() + 'px'
          })
        else
          loader.hide()
      });
    }
    
  });
  

  // Document ready
  $(function(){
    new ImageUploader('#multi_img_upload');
  });

})(jQuery);

Can you please tell me what is url on line 18

'#{ admin_product_images_path(product.id) }'

Is this some code generated from server side ?