Functions In CoffeeScript

Question

I'm trying to convert a function from Javascript to CoffeeScript. This is the code:

function convert(num1, num2, num3) {
    return num1 + num2 * num3;
}

But how I can do that in CoffeeScript?

I'm trying to run the function from an HTML source like this:

<script type="text/javascript" src="../coffee/convert.js"></script>

<script type="text/javascript">
    convert(6, 3, 10);
</script>

But it won't work and I get an error saying: ReferenceError: Can't find variable: convert

How to correct this?

The answers given are correct, but what you really should do instead is get the remaining JS out of your HTML and into an external JS or CoffeeScript file. JS doesn't belong in HTML. — Marnen Laibow-Koser
– Marnen Laibow-Koser, Commented Nov 10, 2011 at 22:27

Community · Accepted Answer · 2017-05-23 12:00:53Z

78

You need to export the convert function to the global scope.
See How can Coffescript access functions from other assets?

window.convert = (num1, num2, num3) ->
  num1 + num2 * num3

edited May 23, 2017 at 12:00

CommunityBot

11 silver badge

answered Jun 1, 2011 at 20:50

lawnsea

6,5811 gold badge26 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Trevor Burnham Over a year ago

This answer is spot-on. It must be emphasized that once attached to window, window.convert can be accessed from anywhere as just convert; but writing convert = creates a variable called convert with local var scope.

Mark Essel Over a year ago

Nice lawnsea, just hit this one today while calling a function from javascript (mixed). I remembered the anonymous scope but forgot Trevor's suggestion to slap it on window to make it callable outside of coffeescript's space

jaime · Accepted Answer · 2011-06-05 00:23:11Z

33

@lawnsea answer is great.

I just want to add some thoughts.

Instead of polluting the global namespace, I prefer to add just one variable to the window object.

window.App = {}

Then, you can have access to App globally and add all your stuff there. the function convert can now be expressed this way:

App.convert = convert = (a, b, c) -> a + b * c

Then, to call the function within the local scope

convert 1,2,3

And now globally

App.convert 1,2,3

answered Jun 5, 2011 at 0:23

jaime

42k10 gold badges85 silver badges52 bronze badges

Comments

twf · Accepted Answer · 2012-03-27 14:28:36Z

17

At the top level of your coffeescript file, this (aka @) should refer to window. So to attach it here, you could use the shorthand:

@convert = (num1, num2, num3) -> num1 + num2 * num3

Note that this pollutes the global namespace, though. The solution posted by jm- is more prudent. But you can replace

window.App = {}

with

@App = {}

The benefit of using @ is that it refers to global in node.js, so you can use the same code to expose your functions in both browser and serverside environments.

answered Mar 27, 2012 at 14:28

twf

3254 silver badges8 bronze badges

Comments

edoloughlin · Accepted Answer · 2011-06-01 21:41:34Z

5

window.convert = (num1, num2, num3) ->
  num1 + num2 * num3

edited Jun 1, 2011 at 21:41

answered Jun 1, 2011 at 19:55

edoloughlin

5,9214 gold badges35 silver badges61 bronze badges

Comments

jrhicks · Accepted Answer · 2011-06-01 20:04:37Z

1

You should check these awesome slides just released today by godfoca http://www.slideshare.net/godfoca/lets-have-a-cup-of-coffeescript Also, you can try code out through-the-web at http://jashkenas.github.com/coffee-script/

convert = (num1, num2, num3) ->
  num1 + num2 * num3

edited Jun 1, 2011 at 20:04

answered Jun 1, 2011 at 19:55

jrhicks

15k9 gold badges45 silver badges57 bronze badges

1 Comment

edoloughlin Over a year ago

Think you have a stray space in there: '- >'

Jasmijn · Accepted Answer · 2011-06-01 19:54:52Z

0

convert = (num1, num2, num3) -> num1 + num2 * num3

answered Jun 1, 2011 at 19:54

Jasmijn

10.7k2 gold badges33 silver badges49 bronze badges

Collectives™ on Stack Overflow

Functions In CoffeeScript

6 Answers 6

2 Comments

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

2 Comments

Comments

Comments

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related