code: function fromSource(src, options) {
      const config = {
          features: {
              FetchExternalResources: ['script'],
              ProcessExternalResources: ['script']
          },
          virtualConsole: jsdom.createVirtualConsole().sendTo(console),
          userAgent: options.userAgent
      };
  
      // The htmlroot option allows root-relative URLs (starting with a slash)
      // to be used for all resources. Without it, root-relative URLs are
      // looked up relative to file://, so will not be found.
      if (options.htmlroot) {
          config.resourceLoader = function(resource, callback) {
              // See whether raw attribute value is root-relative.
              const src = resource.element.getAttribute('src');
              if (src.indexOf('/') === 0) {
                  resource.url.pathname = path.join(options.htmlroot, src);
              }
  
              return resource.defaultFetch(callback);
          };
      }
  
      if (options.inject) {
          config.onload = function(window) {
              if (typeof options.inject === 'function') {
                  options.inject(window);
              } else {
                  require(path.join(__dirname, options.inject))(window);
              }
          };
      }
  
      return new Promise((resolve, reject) => {
          jsdom.env(src, config, (err, res) => {
              if (err) {
                  return reject(err);
              }
              return resolve(res);
          });
      }).then((result) => {
          return new Promise((resolve) => {
              setTimeout(() => resolve(result), options.timeout);
          });
      });
  }
docs: Load a page.
  @param  {String}  src
  @param  {Object}  options
  @return {Promise}