Chaining Promises in Coffeescript

Question

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

return $.getJSON(\'/api/post.json\')         


        

Answer 1

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

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.

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

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.