Vishful thinking…

Moving away from the javascript module pattern

Posted in javascript by viswaug on March 2, 2011

A while ago I had written about using the javascript module pattern to organize code a little better. But off late, I have moved away from using the module pattern because of some reasons which i will outline below. But the pattern to use is really a matter of preference in my opinion. I have now gone back to basics and am using the javascript prototype pattern and have been loving it. Here is why i made the switch

  • the ‘this’ keyword in my class method means what I really expect/want it to mean
  • creating multiple instances of my class doesn’t consume more memory for creating more function instances since all instances use the functions on the prototype
  • the ‘instanceof’ operator can be used to determine if any object is an instance of the class

Here is a simple example illustrating how to create a class. The snippet below creates a class called ‘MyClass’ with the ‘getOption’, ‘calculatePay’, ‘getDisplayPay’ methods.

function MyClass(options) {//constructor
  this.options = options;
};

MyClass.prototype.getOption = function(name) {
  return this.options[name];
};

MyClass.prototype.calculatePay = function(hours) {
  return hours * this.options['hourlyRate'];
};

MyClass.prototype.getDisplayPay = function(hours) {
  return this.getOption('name') + " - " + this.calculatePay(hours);
};

To create an instance of the class above

var inst = new MyClass({‘name’ : ‘Jeff’, ‘hourlyRate’ : 1000});

Also, the following works too

inst.constructor === MyClass; //returns true

if( inst instanceof MyClass ) //evaluates to true

Pretty simple and sweet. Here are a couple of examples of classes written like above

g2kml

g2geojson

I am also using the standalone YUITest for unit testing javascript which doesn’t require the YUI framework which looks more attractive in YUI3. It was a very close call between YUITest and QUnit for the unit testing framework. I went with YUITest because it came with Selenium drivers

YUITest example for g2kml

YUITest example for g2geojson

Advertisements