Code Reuse on Client and Server

Problem

You have created some functionality in CoffeeScript that you wish to use on the client with a web browser and on the server with Node.js.

Solution

Export the functionality in the following manner:

# simpleMath.coffee

# these methods are private
add = (a, b) ->
    a + b

subtract = (a, b) ->
    a - b

square = (x) ->
    x * x

# create a namespace to export our public methods
SimpleMath = exports? and exports or @SimpleMath = {}

# items attached to our namespace are available in Node.js as well as client browsers
class SimpleMath.Calculator
    add: add
    subtract: subtract
    square: square

Discussion

In the above example, we create a new namespace called SimpleMath. If export is available, our class is exported as a Node.js module. If export is not available, then SimpleMath is added to the global namespace and available to our web page.

In Node.js, we can include our module using the require command.

$ node

> var SimpleMath = require('./simpleMath');
undefined
> var Calc = new SimpleMath.Calculator();
undefined
> console.log("5 + 6 = ", Calc.add(5, 6));
5 + 6 =  11
undefined
>

In our web page, we can include our module using by including it as a script.

<!DOCTYPE HTML>
<html lang="en-US">
<head>
    <meta charset="UTF-8">
    <title>SimpleMath Module Example</title>
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
    <script src="simpleMath.js"></script>
    <script>
        jQuery(document).ready(function    (){
            var Calculator = new SimpleMath.Calculator();
            var result = $('<li>').html("5 + 6 = " + Calculator.add(5, 6));
            $('#SampleResults').append(result); 
        });
    </script>
</head>
<body>
    <h1>A SimpleMath Example</h1>
    <ul id="SampleResults"></ul>
</body>
</html>

Result:

A SimpleMath Example

5 + 6 = 11