在咖啡脚本中切换case语句 [英] Switch case statement in coffee script

问题描述

我有几个不同的按钮，调用相同的功能，我想让他们包装在switch语句，而不是使用一堆else if条件。任何帮助将是伟大的！

 事件：
点击.red，.blue，#black， yellow：openOverlay
 
 openOverlay：（e） - > 
 e.preventDefault（）
 e.stopPropagation（）
 
 target = $（e.currentTarget）
 
＃视图应打开
 view = 
 if target.hasClass'red'then new App.RedView 
 else if target.hasClass'blue'then new App.BlueView 
 else if target.is'#black'那么新的App.BlackView 
 else 
 null 
 
＃打开视图
 App.router.overlays.add视图：view if view？ 
   
 
解决方案
   switch  ：
  switch expr 
当expr1时... 
当expr2时... 
 ... 
 else ... 
  
和：
  switch 
 when expr1 then ... 
 when expr2 then ... 
 ... 
 else ... 
  
第二种形式可能会帮助您：
  view = switch 
当target.hasClass'red'然后new App.RedView 
当target.hasClass'blue'然后新App.BlueView 
当target.is'#black'然后新App.BlackView 
 else null 
  
你可以省略 else null 如果未定义是视图的可接受值。您还可以将逻辑包装在（显式）函数中：
  viewFor =（target） 
＃有很多方法可以做到这一点... 
 return new App.RedView if（target.hasClass'red'）
 return new App.BlueView if（target.hasClass'blue '）
 return new App.BlackView if（target.is'#black'）
 null 
 
 view = viewFor target 
  
给你的逻辑一个名字（即包装在一个函数中）通常有助于澄清你的代码。
 
I have a few different buttons that are calling the same function and I would like to have them wrapped in a switch statement instead of using a bunch of else if conditions. Any help would be great!!!
events:
"click .red, .blue, #black, #yellow" : "openOverlay"

openOverlay: (e) ->
  e.preventDefault()
  e.stopPropagation()

target = $(e.currentTarget)

# the view should be opened
view = 
  if target.hasClass 'red' then new App.RedView
  else if target.hasClass 'blue' then new App.BlueView
  else if target.is '#black' then new App.BlackView
  else
    null

# Open the view
App.router.overlays.add view: view if view?

解决方案
There are two forms of switch in CoffeeScript:
switch expr
    when expr1 then ...
    when expr2 then ...
    ...
    else ...
and:
switch
    when expr1 then ...
    when expr2 then ...
    ...
    else ...
The second form might help you:
view = switch
  when target.hasClass 'red' then new App.RedView
  when target.hasClass 'blue' then new App.BlueView
  when target.is '#black' then new App.BlackView
  else null
You could leave out the else null if undefined is an acceptable value for view. You could also wrap the logic in an (explicit) function:
viewFor = (target) ->
    # There are lots of ways to do this...
    return new App.RedView   if(target.hasClass 'red')
    return new App.BlueView  if(target.hasClass 'blue')
    return new App.BlackView if(target.is '#black')
    null

view = viewFor target
Giving your logic a name (i.e. wrapping it in a function) is often useful for clarifying your code.

                        
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