coffeescript总是返回响应对象 [英] coffeescript is always returning the response object

问题描述

我在coffeescript中有以下代码

  getSection =（url） - > 
 req = $ .getJSON url 
 return req.success（data） - > 
 data.section 
  

或

  getSection =（url） - > 
 req = $ .getJSON url 
 req.success（data） - > 
 data.section 
  

我打算返回 data.section 用于函数 getSection 。但它总是返回另一个对象（可能是响应/ ajax对象）。如何提前感谢？

< >解决方案

$。getJSON 是AJAX调用， A 代表异步，因此 getSection 将在 $。getJSON 从服务器获取其响应。基本上，你不能得到 getSection 返回 data.section ，除非你要替换 $ .getJSON 与 $。ajax 并执行同步（即非异步）调用;

通常的解决方案是传递一个回调到 getSection ：

  getSection =（url，callback） - > 
 req = $ .getJSON url 
 req.success（data） - > 
 callback（data.section）
  

然后将你的逻辑放在 callback ，而不是尝试使用 getSection 返回值做某事。

您的 getSection 正在返回 req ，因为这是 req.success 返回，CoffeeScript函数返回其最终值。

i've the following codes in coffeescript

getSection = (url) ->
  req = $.getJSON url
  return req.success (data) ->
    data.section

or,

getSection = (url) ->
  req = $.getJSON url
  req.success (data) ->
    data.section

i intended to return data.section for the function getSection. but it is always returning another object (probably the response/ajax object). how can I force to return the values in data.section from this inner function?

thanks in advance?

解决方案

$.getJSON is an AJAX call and A stands for asynchronous so getSection will return before $.getJSON gets its response back from the server. Basically, you can't get getSection to return data.section unless you want to replace $.getJSON with $.ajax and do a synchronous (i.e. non-asynchronous) call; however, synchronous calls are evil and are being deprecated so you shouldn't use them.

The usual solution is to pass a callback to getSection:

getSection = (url, callback) ->
  req = $.getJSON url
  req.success (data) ->
    callback(data.section)

and then you put your logic in callback rather than trying to do something with the getSection return value.

Your getSection is returning req because that's what req.success returns and CoffeeScript functions return their final value.

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