inhouse.js

    (function(){

        // make a copy of the native window.print
        var _print = this.print;

        // create a new window.print
        window.print = function (window) {
            // if `onbeforeprint` exists, call it.
            if(this.onbeforeprint) onbeforeprint(this); 
            // call the original `window.print`.
            _print.apply(this);
            // if `onafterprint` exists, call it.
            if (this.onafterprint) onafterprint(this);
        }

    }());