implementing-sagas-middleware-3

middleware.js

...
if (handler) {
  const handlerInstance = handler(action);

  let yieldedValue = handlerInstance.next();

  (async () => {
    while (!yieldedValue.done) {
      switch (yieldedValue.value.effect) {
        case 'effect/CALL':
          await yieldedValue.value.payload.apply(null, yieldedValue.value.args)
            .then(res => { yieldedValue = handlerInstance.next(res) })
            .catch(err => { yieldedValue = handlerInstance.throw(err) });
          break;
        case 'effect/PUT':
          store.dispatch(yieldedValue.value.payload);
          yieldedValue = handlerInstance.next();
          break;
        default:
          yieldedValue = handlerInstance.next();
      }
    }
  })();
}
...