CoffeeScript类导致空对象

Question

I have a file 'a.coffee', with the following code:

class Options
  options:
    # ...

  setOption: (name, value) ->
    # ...

  getOption: (name) ->
    # ...

# Export the Options class.
module.exports = Options

And file 'b.coffee':

Options = require './a'
console.log new Options()

Of course, it is expected that when I run b.coffee, I will see this output:

{
  options: ...,
  setOption: function (name, value),
  getOption: function (name)
}

But instead, I get {} .

How can I fix this?

Answer 1

Your expectations are wrong. Everything at the class level goes in the object's prototype so given this:

class C
  p: 6
  m: ->
o = new C

the object o will be empty because there are no instance variables but if you look at the "class" (via Object.prototype.constructor to get the "class" and :: to get the prototype):

o.constructor::p

you'll see things.

If you add some instance variables (ie something that really is part of your object):

class C
  constructor: -> @p = 6

then you'll see them in the object:

c = new C
console.log c
# { p: 6 } will appear in the console