Get class type in CoffeeScript

Question

How can I find that class of an object once it has been instantiated?

class Cat
  constructor: (@name) ->

class Dog
  constructor: (@name) ->

cat = new Cat "Kitty"
dog = new Dog "Doggy"

if (cat == Cat)  <- I want to do something like this

score 29 · Accepted Answer · answered Mar 01 '12 at 23:03

29

Just change the == to instanceof

if(cat instanceof Cat)

answered Mar 01 '12 at 23:03

Sandro

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thanks for the specific code help. It will help me with my project in figuring out the object type in an array. – Alexis Mar 01 '12 at 23:04
is there a way though to get the name of the object with guessing and checking? – Alexis Mar 01 '12 at 23:10
http://stackoverflow.com/questions/7087712/get-the-model-type-for-a-passed-in-backbone-js-model-instance – sye May 04 '12 at 05:44
Actually this question might be helpful as well. For some reason I never saw your comment @AlexisK http://stackoverflow.com/questions/332422/how-do-i-get-the-name-of-an-objects-type-in-javascript – Sandro May 04 '12 at 15:16
From the response in the question above, the equivalent CoffeeScript could be: http://jsfiddle.net/SLtTs/ – Sandro May 04 '12 at 15:22

score 7 · Answer 2 · edited Mar 21 '17 at 21:49

If you wanted to know the type name of a particular object (which is what I was just looking for when I found this question), you can use the syntax {object}.constructor.name

for example

class Cat
    constructor: (@name) ->

  class Dog
    constructor: (@name) ->

  cat = new Cat()
  dog = new Dog()

  console.log cat.constructor.name
  console.log dog.constructor.name

which will output

Cat
Dog

Cory Dolphin · Answer 3 · 2012-03-02T18:56:48.940

5

The way to do this is to check the type of an object using either

instanceof

or

typeof

i.e.

if (obj instanceof Awesomeness){
//doSomethingCrazy();
}

Just as in JavaScript, Coffee Script does not provide any abstraction over these functions

edited Mar 02 '12 at 18:56

answered Mar 01 '12 at 22:58

Cory Dolphin

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is there a way though to get the name of the object with guessing and checking? – Alexis Mar 01 '12 at 23:10
@Alexis I think typeof is what you want. – Ryan_IRL Jul 29 '14 at 19:44

score 2 · Answer 4 · edited Dec 16 '14 at 15:10

2

AFAIU, the general solution would be using @constructor - Useful when you don't know or don't want to specify the class name.

There was even a discussion regarding making @@ a shortcut for it.

edited Dec 16 '14 at 15:10

Leonid Beschastny

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answered Aug 04 '13 at 12:34

m0she

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Get class type in CoffeeScript

4 Answers4