Function to intercept functions calls even to nativ functions.

intercept-function.js

function interceptFunction (object, fnName, options) {
    var noop = function () {};
    var fnToWrap = object[fnName];
    var before = options.before || noop;
    var after = options.after || noop;

    object[fnName] = function () {
        before.apply(this, arguments);
        var result = fnToWrap.apply(this, arguments);
        after.apply(this, arguments);
        return result
    }
}