gistfile1.txt

// ## $.withAdvice
//
// Borrowed by [Flight](https://github.com/flightjs/flight).
//
// `withAdvice` is a mixin that defines `before`, `after` and `around` methods.
//
// These can be used to modify existing functions by adding custom code. All
// components have advice mixed in to their prototype so that mixins can augment
// existing functions without requiring knowledge of the original
// implementation.
//
// Mixins will typically use the after method to define custom behavior for the
// target component.
//
// ### Example
//
//     var foo = {
//         print: function () {
//             console.log("Hello");
//         }
//     }
//     $.withAdvice.call(foo);
//     foo.after("print", function () {
//         console.log("world");
//     });
//
//     foo.print(); //logs Hello world
//
(function ($) {
    "use strict";

    $.withAdvice = function () {

        var advice = {
            around: function (base, wrapped) {
                return function composedAround() {
                    var i = 0, l = arguments.length, args = new Array(l + 1);
                    args[0] = base.bind(this);
                    for (; i < l; i += 1) {
                        args[i + 1] = arguments[i];
                    }

                    return wrapped.apply(this, args);
                };
            },

            before: function (base, before) {
                return function composedBefore() {
                    before.apply(this, arguments);
                    return base.apply(this, arguments);
                };
            },

            after: function (base, after) {
                return function composedAfter() {
                    var res = base.apply(this, arguments);
                    after.apply(this, arguments);
                    return res;
                };
            }
        };

        function unlockProperty(obj, op) {
            op.call(obj);
        }

        ["before", "after", "around"].forEach(function (m) {
            this[m] = function (method, fn) {

                unlockProperty(this, function () {
                    if (typeof this[method] === "function") {
                        this[method] = advice[m](this[method], fn);
                    } else {
                        this[method] = fn;
                    }

                    return this[method];
                });
            };
        }, this);

        return advice;
    };
}(jQuery));