redux-state-sync/example/src/reducers/todos.js

A middleware for redux to sync state in different tabs

const todos = (state = [], action) => {
    switch (action.type) {
        case 'ADD_TODO':
            return [
                ...state,
                {
                    id: action.id,
                    text: action.text,
                    completed: false,
                },
            ];
        case 'TOGGLE_TODO':
            return state.map(todo => (todo.id === action.id ? { ...todo, completed: !todo.completed } : todo));
        default:
            return state;
    }
};
export default todos;