Easy create a redux reducer

create-reducer.js

export default function createReducer(initialState, handlers) {
    return function reducer(state = initialState, action) {
        let nextState = state;

        if ({}.hasOwnProperty.call(handlers, '*')) {
            nextState = handlers['*'](nextState, action);
        }

        if ({}.hasOwnProperty.call(handlers, action.type)) {
            return handlers[action.type](nextState, action);
        }
        return nextState;
    };
}

z_how-to-use.js

export default createReducer(initialState, {
    'my-action': updateSomething
    '*': runOnAllActions
});