webcomponentsjs/src/WebComponents/build/boot.js

/**
 * Copyright (c) 2014 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */

window.WebComponents = window.WebComponents || {};

// process flags
(function(scope){

  // import
  var flags = scope.flags || {};

  var file = 'webcomponents.js';
  var script = document.querySelector('script[src*="' + file + '"]');

  // Flags. Convert url arguments to flags
  if (!flags.noOpts) {
    // from url
    location.search.slice(1).split('&').forEach(function(o) {
      o = o.split('=');
      o[0] && (flags[o[0]] = o[1] || true);
    });
    // from script
    if (script) {
      for (var i=0, a; (a=script.attributes[i]); i++) {
        if (a.name !== 'src') {
          flags[a.name] = a.value || true;
        }
      }
    }
    // log flags
    if (flags.log && flags.log.split) {
      var parts = flags.log.split(',');
      flags.log = {};
      parts.forEach(function(f) {
        flags.log[f] = true;
      });
    } else {
      flags.log = {};
    }
  }

  // Determine default settings.
  // If any of these flags match 'native', then force native ShadowDOM; any
  // other truthy value, or failure to detect native
  // ShadowDOM, results in polyfill
  flags.shadow = (flags.shadow || flags.shadowdom || flags.polyfill);
  if (flags.shadow === 'native') {
    flags.shadow = false;
  } else {
    flags.shadow = flags.shadow || !HTMLElement.prototype.createShadowRoot;
  }

  // forward flags
  if (flags.register) {
    window.CustomElements = window.CustomElements || {flags: {}};
    window.CustomElements.flags.register = flags.register;
  }

  // export
  scope.flags = flags;
})(WebComponents);