How to do "if undefined" in coffeescript?

Question

How would I get this in CoffeeScript? This is the JS that I am trying to get :

if (value === undefined) {
  return model.get('isCompleted');
}

Basically, When I am trying this :

if value is undefined
  model.get 'isCompleted'

I am getting this in the JS :

if (value === void 0) {
  model.get('isCompleted');
}

Is there no way to display "undefined" without :

if value is `undefined`

I somehow don't want to use ``.

What's wrong with `value === void 0`? `void 0` returns `undefined`. It's often used because it is possible in older browsers to overwrite the value of `undefined` with something else. — Felix Kling, Mar 02 '14 at 18:57
See [What does `void 0` mean?](http://stackoverflow.com/q/7452341/218196) — Felix Kling, Mar 02 '14 at 18:59

score 3 · Answer 1 · answered Mar 02 '14 at 19:04

In case you're not aware of the CoffeeScript existential operator, that makes it real easy to check whether a variable is defined (i.e. it's not undefined or null). If it doesn't matter to you whether value is null or undefined, I'd use that. Use it like so:

if !value?
  model.get 'isCompleted'

How to do "if undefined" in coffeescript?

1 Answers1