CoffeeScript类字段未定义

Question

This code is passing in a function and is not carrying over the state of my EmployeesController object. What can i do to bind my EmployessController object to the focus event?

class @EmployeesController 
  constructor: (@dateInput) ->
    @dateInput.focus(@searchInputGainedFocus)


  searchInputGainedFocus: ->
    console.debug @dateInput

In other words, console.debug prints undefined when i give dateInput focus.

Answer 1

Use the "fat arrow" ( => ) to bind searchInputGainedFocus to the object:

The fat arrow => can be used to both define a function, and to bind it to the current value of this , right on the spot. This is helpful when using callback-based libraries like Prototype or jQuery, [...]

So define searchInputGainedFocus like this:

class @EmployeesController 
  constructor: (@dateInput) ->
    @dateInput.focus(@searchInputGainedFocus)

  searchInputGainedFocus: =>
    console.debug @dateInput