Edit in JSFiddle

$(document).ready(function() {
    var _opt = null;
    $.fn.QR = function(op) {
        _opt = $.extend({}, $.fn.QR.defaults, op);
        return this.each(function() {
            var code = "https://chart.googleapis.com/chart?chs=150x150&cht=qr&chl={url}&choe=UTF-8";
            var qrc = code.replace();
            qrc = qrc.replace(/{url}/g, escape(_opt.url));
            $(this).append("<img src='" + qrc + "'>");
        });
    };
    $.fn.QR.defaults = {
        url: window.location
    };
});
$("#qrcode").QR({
    url: "http://kachibito.net"
});

<span id="qrcode"></span>