Some basic AOP style functions.

aop.js

var before = function(fn, pre) {
        return function() {
            pre.apply(this, arguments);
            return fn.apply(this, arguments);
        };
    },
    after = function(fn, aft) {
        return function() {
            var result = fn.apply(this, arguments);
            aft.apply(this, result);
            return result;
        };
    },
    around = function(fn, pre, aft) {
        return function() {
            var result;
            pre.apply(this, arguments);
            result = fn.apply(this, arguments);
            aft.apply(this, result);

            return result;
        };
    };

example

console.log = around(console.log, function() {
    console.info("tadaaa a log message is coming");
}, function () {
    console.info("tadaaa a log message has been");
});

will result in

console.log("foo");
// "tadaaa a log message is coming"
// "foo"
// "tadaaa a log message has been"