code: function polyfill() {
          if (navigator.userAgent.match(/MSIE/) ||
              navigator.userAgent.match(/Trident/) ||
              navigator.userAgent.match(/Edge/)) {
              // Internet Explorer's native IndexedDB does not support compound keys
              compoundKeyPolyfill();
          }
      }
docs: Polyfills missing features in the browser's native IndexedDB implementation.
  This is used for browsers that DON'T support WebSQL but DO support IndexedDB