text: // Copyright 2018 The Immersive Web Community Group
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  
  // The above copyright notice and this permission notice shall be included in
  // all copies or substantial portions of the Software.
  
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  /*
  Provides a simple way to get values from the query string if they're present
  and use a default value if not. Not strictly a "WebGL" utility, but I use it
  frequently enough for debugging that I wanted to include it here.
  
  Example:
  For the URL http://example.com/index.html?particleCount=1000
  
  QueryArgs.getInt("particleCount", 100); // URL overrides, returns 1000
  QueryArgs.getInt("particleSize", 10); // Not in URL, returns default of 10
  */
  
  let urlArgs = null;
  window.onhashchange = function() {
    // Force re-parsing on next access
    urlArgs = null;
  };
  
  function ensureArgsCached() {
    if (!urlArgs) {
      urlArgs = {};
      let query = window.location.search.substring(1) || window.location.hash.substring(1);
      let vars = query.split('&');
      for (let i = 0; i < vars.length; i++) {
        let pair = vars[i].split('=');
        urlArgs[pair[0].toLowerCase()] = decodeURIComponent(pair[1]);
      }
    }
  }
  
  export class QueryArgs {
    static clearCache() {
      urlArgs = null;
    }
  
    static getString(name, defaultValue) {
      ensureArgsCached();
      let lcaseName = name.toLowerCase();
      if (lcaseName in urlArgs) {
        return urlArgs[lcaseName];
      }
      return defaultValue;
    }
  
    static getInt(name, defaultValue) {
      ensureArgsCached();
      let lcaseName = name.toLowerCase();
      if (lcaseName in urlArgs) {
        return parseInt(urlArgs[lcaseName], 10);
      }
      return defaultValue;
    }
  
    static getFloat(name, defaultValue) {
      ensureArgsCached();
      let lcaseName = name.toLowerCase();
      if (lcaseName in urlArgs) {
        return parseFloat(urlArgs[lcaseName]);
      }
      return defaultValue;
    }
  
    static getBool(name, defaultValue) {
      ensureArgsCached();
      let lcaseName = name.toLowerCase();
      if (lcaseName in urlArgs) {
        return parseInt(urlArgs[lcaseName], 10) != 0;
      }
      return defaultValue;
    }
  }
  