Ever wanted to debounce only the AJAX portion of a Backbone.Model.save call, but still have the client-side attributes update immediately? This mixin uses composition and _.compose to give you that ability :D

debounced_backbone_model_save_mixin.coffee

app.mixins.addDebounceToModelSave = (model, milliseconds) ->

  debouncedSaver = _.debounce(model.save, milliseconds)

  setter = (attrs, options) ->
    {attributes: model.set(attrs).attributes, options}

  saver = (args) ->
    debouncedSaver.call(model, args.attributes, args.options)

  model.save = _.compose(saver, setter)

usage.coffee

# some view that increments a quantity by 1 every time a user clicks
# we dont want to trigger an AJAX call on fast successive clicks... 

app.views.QuantityView = Backbone.View.extend          
  
  events:
    "click .increment" : "incrementByOne"          
  
  initialize: ->
    # but we want our model.attributes to update instantly 
    # so our view can keep the DOM fragment representing quantity in sync
    @model.on("change:quantity", @updateQuantityDisplay)
    
    # so we mix in the behaviour
    app.mixins.addDebounceToModelSave(@model, 750) 
    
  # now incrementByOne can be called multiple times in succession...
  incrementByOne: =>
    # our attributes update immediately, and we only have 1 AJAX call to the server
    # but we only have to call model.save instead of model.set + model.save
    @model.save({quantity: @model.get('quantity') + 1})
    
  updateQuantity: (__, quantity) =>
    @$(".quantity").text(quantity)