Knockout Lazy ViewModel

lazy.js.coffee

class OPL.ViewModels.Lazy extends OPL.ViewModels.Base
  ###
  lazyFlag is a string that holds the flag's name.
  When the flag changes from false to true, it creates
  the lazy objects and methods. When it changes from true
  to false, it destroys the lazy objects and methods.
  ###
  lazyFlag: "editMode"
  
  constructor: ->
    super()
    @_subscribe @[lazyFlag], (shouldLoad) =>
      if shouldLoad then @lazyLoad() else @destroyLazyObjects()
        
  lazyLoad: ->
    ###
    Load the observable values that the view model needs
    when its `editMode` flag is set to true
    ### 
    @editedTitleContent = ko.observable ""
    @editedDueBy = ko.observable ""
    # Methods that are needed only when `editMode` is set to true
    @updateTodoGroup = ->
      # Do something
    
  destroyLazyObjects: ->
    ###
    Destroy the observable values and methods that the view model 
    doesn't need when its `editMode` flag is set to false
    ###
    delete @editedTitleContent
    delete @editedDueBy
    delete @updateTodoGroup

dispose instead of delete