LocalForage setDriver Looper

es7

async function setDriver(driverNames) {
  for (var driverName of driverNames) {
    if (this.supports(driverName) {
      try {
        let driver = await this.getDriver(driverName).then(driver => driver._initDriver());
        if (driver) {
          return Promise.resolve(driver);
        }
      } catch (e) { }
    }
  }
  return Promise.reject('No supported driver found!');
}

setDriverLooper.js

var localForageDriverOrder = [localforage.INDEXEDDB, localforage.LOCALSTORAGE, localforage.WEBSQL];

var setDriverPromise = new Promise(function(resolve, reject) {
	var drivers = localForageDriverOrder.slice();
	var crntDriverPromise = Promise.resolve();
	crntDriverPromise.then(driversPromiseLoop);

	function driversPromiseLoop(){
		var driver = null;
		while (driver = drivers.shift()) {
			if (localforage.supports(driver)) {
				crntDriverPromise = localforage.setDriver(driver);
				return crntDriverPromise.then(function(){
					resolve();
				}).catch(driversPromiseLoop);
			}
		}
		reject('No driver');
	}
});

setDriverLooperGenerators.js

new Promise((resolve, reject) => {
    runGeneratorOnce(myPromiseGenerator, initialValue);

    function runGeneratorOnce(pg, result) { var status = pg.next(result);
        if (status.done) { reject('No driver'); return; }

        status.value.then(resolve).catch(value => {
            return runGeneratorOnce(pg, value);
        });
    }

    function* myPromiseGenerator() {
        for (var i = 0, len = drivers.length; i < len; i++) {
            if (localforage.supports(driver)) {
                yield localforage.setDriver(driver);
            }
        }
    }
});