javascript - CoffeeScript 类字段未定义

Question

这段代码传入了一个函数，并没有继承我的 EmployeesController 对象的状态。我该怎么做才能将我的 EmployessController 对象绑定(bind)到焦点事件？

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


  searchInputGainedFocus: ->
    console.debug @dateInput

换句话说，当我给 dateInput 焦点时，console.debug 打印未定义。

Answer 1

使用 "fat arrow" (=>)将 searchInputGainedFocus 绑定(bind)到对象:

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, [...]

所以像这样定义searchInputGainedFocus:

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

  searchInputGainedFocus: =>
    console.debug @dateInput