Please critique my TODO App in React w/ Redux:

// React Component const TodoApp = ({todos, inputText, onInputChange, onAdd, onDelete}) => {     const numbers = range(todos.length);     const zipped  = zip(numbers, todos);      return (         <div>             <h1>TODO!</h1>             <ul>{zipped.map( (z) =>                     <li key={z[0].toString()}>                         {z[1].text}                         <button onClick={() => onDelete(z[0])}>delete</button>                     </li>                 )}                 <li>                     <input type="text" value={inputText} onChange={onInputChange}/>                     <button onClick={onAdd}>add</button>                 </li>             </ul>         </div>     ); };  // Redux (State) const ADD = 'ADD'; const UPDATE_INPUT_TEXT = 'UPDATE_INPUT_TEXT'; const DELETE='DELETE';  function todo(state = {todos: [], inputText: ""}, action) {     switch(action.type) {         case ADD:             return {               todos: state.todos.concat( {                 text: state.inputText               }),               inputText: ''             };         case UPDATE_INPUT_TEXT:             return {                 todos: state.todos,                 inputText: action.newInputText             };         case DELETE:             const filtered = state.todos.filter( (e, index) => index !== action.index);             return {                 todos: filtered,                 inputText: ''             };         default:             return state;     } }  const store = createStore(todo);  const renderTodo = () => {     const st = store.getState();     ReactDOM.render(         <TodoApp todos={st.todos}                  inputText={st.inputText}                  onInputChange={event =>                      store.dispatch({type: UPDATE_INPUT_TEXT, newInputText: event.target.value})                  }                  onAdd={() => store.dispatch({type: ADD})}                  onDelete={(index) => store.dispatch({type: DELETE, index: index})}          />,         document.getElementById('root')     ) };  store.subscribe(renderTodo); renderTodo();