链接承诺在咖啡 [英] Chaining Promises in Coffeescript

问题描述

有没有办法在Coffeescript中链接 Promises 。例如，考虑以下JavaScript代码，

Is there a way to chain Promises together in Coffeescript. For example, consider the following javascript code,

return $.getJSON('/api/post.json')
  .then(function(response) {
    // do something
  })
  .then(function(response) {
    // do something
  })
  .then(null, function(err) {
    // do something
  });

每个然后是最后的然后需要由函数返回。
目前我在coffeescript写这个，

Each of the then's is optional, and the final then needs to be returned by the function. Currently I am writing this in coffeescript as,

promise = $.getJSON('/api/post.json')
promise = promise.then (response) ->
  // do something

promise = promise.then (response) ->
  // do something

promise = promise.then null, (err) ->
  // do something

return promise

更好的办法做到这一点？谢谢。

Is there a better way to do this? Thanks.

推荐答案

Ezekiel显示正确的方法，但它不需要函数周围的括号。只要做：

Ezekiel shows the right way, but it doesn't need the parentheses around the functions. Just do:

$.getJSON '/api/post.json' # As of CoffeeScript 1.7, you don't need the parentheses here either.
.then (response) ->
  # do something
  response # if you would not return anything, promise would be fulfilled with undefined
.then (response) ->
  # do something
  undefined # necessary to prevent empty function body
.then null, (err) ->
  # handle error

我觉得很奇怪。
当你需要同时添加onRejected和onFulfilled处理程序时，比较混乱的一件事。

I think it's surprisingly clean. The one thing that's relatively messy is when you need to add onRejected and onFulfilled handlers at the same time.

注意：我上次检查时，工作在CoffeeScript Redux，但是这是几个月前。

Note: Last time I checked, this did not work in CoffeeScript Redux, but this was a few months ago.

注意2：在每个函数中至少需要一行实际代码（即不只是一个注释）身体为这工作。通常情况下，你会的，所以这不是一个大问题。

Note 2: You need at least one line of actual code (i.e. not just a comment) in each function body for this to work. Typically, you will, so it's not a big issue.

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