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An aop library that's compatible w/ the context bindings underscore.js and lodash.js.

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A lot of people use Aspect Oriented Programming (AOP) in JS. It's often called monkey-patching and can be exemplified w/ a common "pattern" I see rather frequently:

var originalMethod = obj[methodName];
obj[methodName] = function advisor () {
    // Do some stuff.
    return originalMethod.apply(this, arguments);

The key here is that the replaced reference modifies the behavior for all users of obj. However, if one of those users happens to do _.bind(obj[methodName], obj) before that aspect, then calls their bound function, it will not lead to advisor being called. This is because the bound function holds a pointer to the original function rather than the advisor.

To get around this, I'm aspecting _.bind, so that the newly created function will expose a private (as in it's mine, leave it alone) guid. Later, when the bound function is called, I look at all the methods on the calling context and figure out if there's an advisor that should be called instead of the original function.


Check out the tests for yourself. Seems ok to me, but I'm happy to look into the things I missed.


I'm hoping to achieve/accomplish:

  • Provide before, after, and around support, that doesn't fork the pointer when _.bind has been called.
  • Provide support for almost any environment.
  • Provide reasonable performance.

Helping Out

If you want to help out, feel free to file pull requests.

To run the tests, ensure you have a recent version of NodeJS (>=0.8). Then, do:

git clone /path/to/your/fork
cd underscore-aop
npm install # npm comes w/ recent versions of node.
npm test # Should pass.

Please, ensure all current tests run and any new features have reasonable test coverage. (Checkout coverjs-gold if you're interested in this sorta thing.)