In a previous post, I showed off prototype's 'wrap' function, which gives JavaScript some AOP capabilities.

jQuery, a tool that I'm more familiar with, doesn't have an equivalent function that I know of. But there is a jQuery AOP plugin that provides a great AOP framework to your JavaScript. 

While 'wrap' is akin to 'interception' style AOP, jQuery-aop includes some 'boundary' style aspects (as well as replacement/interception), including:

• before a method
• after a method
• when a method throws an exception
• when a method completes (exception or not)
• "around" a method
• replace a method (i.e. an "introduction")

There is some good API documentation available. Here's a little 101 example using "before" and "after":

Just paste that into an HTML file and run it in your browser, and you should get two alert messages. Since it's JavaScript, you can apply AOP to built-in functions like String.replace, or jQuery functions, just as easily as you can functions that you've written.