Coffeescript / Javascript变量范围 [英] Coffeescript/Javascript variable scope
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问题描述
我不太确定为什么我没有从Cf()中定义的匿名函数的上下文中访问@date(this.date)变量
I'm not really sure why i do not have access to the @date (this.date) variable from the context of the anonymous function defined in C.f()
class C
constructor: () ->
@date = new Date()
f: () ->
$(document).keydown( (e) ->
alert(@date)
)
有人可以评论吗?
推荐答案
$ c> keydown 事件处理程序, this
值不会引用您的对象,它将引用DOM元素。
This is happening because inside the keydown
event handler, the this
value will not refer to your object, it will refer to the DOM element.
为此,您可以使用 =>
(胖箭头),将绑定处理程序的 this
值到父 this
:
For that purpose, you can use =>
(the fat arrow), that will bind the handler's this
value to the parent this
:
class C
constructor: () ->
@date = new Date()
f: () ->
$(document).keydown( (e) =>
alert(@date)
)
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