At my current project we did some aspect-oriented programming for adding logging framework. Project we worked on is a cordova based ios application. Most of the project is html and angular-js application which parts of it as native. To ensure we don’t have logging logic scattered across the code we used aop approach for the adding logging feature.

I have been wanting to play around with basic aop with JQuery code. This is my attempt at it.

For those hearing about AOP for the first time, this is a quick definition I pulled

Aspect-Oriented Programming (AOP) complements OO programming by allowing the developer to dynamically modify the static OO model to create a system that can grow to meet new requirements. Just as objects in the real world can change their states during their lifecycles, an application can adopt new characteristics as it develops. We can often keep this additional code in a single location rather than having to scatter it across the existing model, as we would have to if we were using OO on its own.

Overview of Aspect Oriented Programming by Graham O’Regan http://www.onjava.com/pub/a/onjava/2004/01/14/aop.html

Key Terms

• Aspect: cross-cutting concerns in stand-alone modules
• Advice: action taken by the aspect
• Join-point: a point during the execution of a program
• Pointcut: a join-point where advice should be executed

Code

https://github.com/singhgarima/js-aop

My Approach

• I have introduced few extension methods (after, before and around), by modifying the prototype property of Function type. This modifies all functions created using new Function(...) or function (...) {...}, and hence introduces these extendion methods on all objects of type Function. (A really good introduction to prototypes can be found here).

• In these extension functions, we are modifying the original definition of the exisiting methods (after/before/around which we want to introduce our advice). We are getting the original definition, from prototype chain on the object. In the modified definition, we call our advice function, at the expected pointcut.