bookmarklet boilerplate

bookmarklet-boilerplate.js

javascript:(function(){

// avoid the bookmarklet activating more than once
if (window.MyNamespace) {
    return;
}
window.MyNamespace = { };

var version = 1,
    script  = document.createElement('script');

script.setAttribute('type', 'text/javascript');
script.setAttribute('charset', 'UTF-8');
script.setAttribute('src', 'http://example.com/mynamespace.js?r=' + Math.random());
document.documentElement.appendChild(script);

script.onload = script.onreadystatechange = function() {
    var rs = script.readyState;
    if (!rs || rs === 'loaded' || rs === 'complete') {
        script.onload = script.onreadystatechange = null;

        // initialise or warn if older version
        if (version !== window.MyNamespace.version) {
            alert('This bookmarklet is out of date!');
        } else {
            window.MyNamespace.init();
        }
    }
};

}());

mynamespace.js

window.MyNamespace = (function(window, document, undefined){
  var app = {
    // increment to expire active bookmarklets
    version  : 1
  };

  app.init = function () {
    window.alert('yes!');
  };

  return app;
})(window, window.document);