src/adapters/websql/valid-browser.js

function valid() {
  // SQLitePlugin leaks this global object, which we can use
  // to detect if it's installed or not. The benefit is that it's
  // declared immediately, before the 'deviceready' event has fired.
  return typeof openDatabase !== 'undefined' ||
    typeof SQLitePlugin !== 'undefined';
}

export default valid;