Redux Action Matchers

What it is?

It's a set of functions that allows easier work in reducers and middleware when matching multiple actions at once not only by threir type property but also by their content.

Installation

npm install action-matchers

Example usage

createReducer()

import { createReducer } from "action-matchers";

type State = {
  temperature: string;
  count: number;
  numberOfCalls: number;
  numberOfCallsWithSecretString: number;
};

const initialState: State = {
  temperature: "0C",
  count: 0,
  numberOfCalls: 0,
  numberOfCallsWithSecretString: 0,
};

function increaseCount(count: number) {
  return {
    type: "increaseCount",
    payload: count,
  };
}

function setTemperature(temperature: string) {
  return {
    type: "setTemperature",
    payload: temperature,
  };
}

function ping() {
  return {
    type: "ping",
    meta: "secret string",
  };
}

function signSecretly() {
  return {
    type: "sign_SECRET",
  };
}

type IncreaseCount = ReturnType<typeof increaseCount>;
type SetTemperature = ReturnType<typeof setTemperature>;

const metricsReducer = createReducer<State>(
  [
    [
      "increaseCount",
      (state, action: IncreaseCount) => ({
        ...state,
        count: state.count + action.payload,
      }),
    ],
    [
      "setTemperature",
      (state, action: SetTemperature) => ({
        ...state,
        temperature: action.payload,
      }),
    ],
    [
      "increaseCount",
      "setTemperature",
      "ping",
      (state, action) => ({
        ...state,
        numberOfCalls: state.numberOfCalls + 1,
      }),
    ],
    [
      (action: any) => action.meta === "secret string",
      /_SECRET$/,
      (state, action) => ({
        ...state,
        numberOfCallsWithSecretString:
          state.numberOfCallsWithSecretString + 1,
      }),
    ],
  ],
  initialState
);

let state = metricsReducer(undefined, setTemperature("3C")); 
// Returned:
// {
//   count: 0,
//   temperature: "3C", <--
//   numberOfCalls: 1, <--
//   numberOfCallsWithSecretString: 0
// }

state = metricsReducer(state, increaseCount(3));
// Returned
// {
//   count: 3, <--
//   temperature: "3C",
//   numberOfCalls: 2, <--
//   numberOfCallsWithSecretString: 0
// }

state = metricsReducer(state, ping());
// Returned
// {
//   count: 3,
//   temperature: "3C",
//   numberOfCalls: 3, <--
//   numberOfCallsWithSecretString: 1 <--
// }

state = metricsReducer(state, signSecretly());
// Returned
// {
//   count: 3,
//   temperature: "3C",
//   numberOfCalls: 3,
//   numberOfCallsWithSecretString: 2 <--
// }

TODO

• More runtime type checking
• Better documentation
• Allow to skip action param in reducer

License

Apache License Version 2.0

Authors

• Rytis Alekna