boilerplate_bookmarklet.js

(function(){
  if (typeof boilerplate_bookmarklet == 'undefined') {
    var stylesheet_url = 'http://example.com/bookmarklet.css';
    var script_url = 'http://example.com/bookmarklet.js';
    
    var head = document.getElementsByTagName('head')[0] || document.documentElement;
    var stylesheet = document.createElement('link');
    
    stylesheet.setAttribute('rel', 'stylesheet');
    stylesheet.setAttribute('type', 'text/css');
    stylesheet.setAttribute('href', stylesheet_url);
    head.appendChild(stylesheet);
    
    var script = document.createElement('script');
    script.setAttribute('type', 'text/javascript');
    script.setAttribute('src', script_url);
    head.appendChild(script);
  } else {
    boilerplate_bookmarklet.init();
  }  
})();