Design Primitives in Javascript: Example Modules, Classes, Functions

Okay, so we defined the modules I'm using in the last post; here, I'll show you the code associated with the version, date, and random modules, and explain what it's doing.

We'll start with the version module as it's the simplest:

(version.js)

exports.version = {
major: 1,
minor: 0,
patch: 0,
status: 'gold'
}

That's it.  Notice, this is an implementation of the versioning interface we defined previously.  We're exporting the version information in an object literal, in the version property, so you reference it from including files using require like this (this assumes side-by-side installation of library files with the server script):

var version = require('./version').version;

The date generator is a little more complex, but not very:

(date.js)

exports.date = function() {


  var _date_generator = function() {
    this.generate = function() {
      return new Date().toString();
    }
  }

  return {
    Generator: _date_generator
  }
}();

Note I've used the module pattern here.  That allows me to define the Generator class based on the private implementation class named _date_generator.  I include and use this class this way:

var date = require('./date').date;
...
var generator = new date.Generator();
var date = generator.generate();

Finally, the random number generating class, using a nifty private variable:

(random.js)

exports.random = function() {

  var _random_generator = function(scale) {

    var _scale = scale;

    this.generate = function() {
      return Math.floor(
        Math.random() 
        * _scale)
      .toString();
    }
  }

  return {
    Generator: _random_generator
  }
}();

Again I use the module pattern, and this time as an added bonus, I use a private variable (i.e. _scale, in the _random_generator class).  Include and use like this:

var random = require('./random').random;
var SEED = 10;
...
var generator = new random.Generator(SEED);
var randomNumber = generator.generate();

And finally, notice that both generator classes adhere to the Generator interface defined in the previous post!  Anyway, that's it for the modules that do the domain work of the service.  Next I'll go into how to get this to work with the network communication plumbing in Node.js.