Using a Definition to identify Actions

You can use the isType() helper method Definitions can identify a plain Redux Action as one of its members using the Definition.is() method.

While Definition.is() would be handy for writing Reducers too, the TypedReducer class is much better suited for the job.

Example

import { isType } from "redoodle";
import { AddMessage } from "./actions";

// assuming AddMessage is created using defineAction(), as in the section "Using Definitions":
//
// const AddMessage = defineAction("AddMessage")<{
//   message: string;
//   author: string;
// }>();
//

const action: Action = yield receiveActionFromServer();

if (isType(action, AddMessage.TYPE)) {
  // isType() is a TypeScript type guard, which narrows
  // the plain Action object into the much more explicit typing
  //
  //    action ~> {
  //      type: "AddMessage",
  //      payload: {
  //        message: string;
  //        author: string;
  //      }
  //    }
  //
  console.log(`${action.author}: ${action.message}`);
}

TypeScript definition

function isType<T>(action: Action, type: TypedActionString<T>): action is TypedAction<T>;