August 18, 2016 09:14
diff --git a/index.html b/index.html
 <!DOCTYPE html>
 <html>
 <head>  
  <script src="https://fb.me/react-15.3.0.min.js"></script>
  <script src="https://fb.me/react-dom-15.3.0.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/redux/3.5.2/redux.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/react-redux/4.4.5/react-redux.js"></script>
  <meta charset="utf-8">
  <title>JS Bin</title>
 </head>
 <body>
  <div id="root"></div>
 <script id="jsbin-javascript">
 /* global ReactRedux, Redux, ReactDOM */

 ////////////////////////////////////////////////
 //
 // Imports
 //

 'use strict';

 var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };

 function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) arr2[i] = arr[i]; return arr2; } else { return Array.from(arr); } }

 var _ReactRedux = ReactRedux;
 var connect = _ReactRedux.connect;
 var Provider = _ReactRedux.Provider;
 var _Redux = Redux;
 var combineReducers = _Redux.combineReducers;
 var createStore = _Redux.createStore;

 ////////////////////////////////////////////////
 //
 // Reducers (except root, see bottom)
 //

 // 2nd level reducer
 // Here, `state` refers to the array of todo objects
 var todos = function todos(state, action) {
  if (state === undefined) state = [];

  console.log("todos reducer called");
  switch (action.type) {
    // Returns a new array of todos, containing the added todo as described by `action`.
    // The new todo is constructed by delegating to the `todo` reducer.
    case 'ADD_TODO':
      console.log('todos ADD_TODO');
      // ... below is ES6 "spread operator" (arrays only)
      return [].concat(_toConsumableArray(state), [todo(undefined, action)]);
    // Returns a new array of todos, with an individual todo's completed status
    // toggled as identified by `action.id`.
    // Must operate on entire list (seems wrong somehow).
    case 'TOGGLE_TODO':
      console.log('todos TOGGLE_TODO');
      return state.map(function (t) {
        return todo(t, action);
      });
    default:
      return state;
  }
 };

 // 2nd level reducer
 // Here, `state` refers to a simple configuration string (enum/atom)
 // Remember, we are only returning the state we are concerned with
 var visibilityFilter = function visibilityFilter(state, action) {
  if (state === undefined) state = 'SHOW_ALL';

  console.log("visibilityFilter reducer called");
  switch (action.type) {
    case 'SET_VISIBILITY_FILTER':
      return action.filter;
    default:
      return state;
  }
 };

 // 3rd level reducer.
 // Here, `state` refers to a single todo object.
 var todo = function todo(state, action) {
  console.log("todo reducer called");
  // Remember, no mutation.
  // Initial state is considered (or not, in the ADD_TODO case),
  // and used to construct a new state object, always.

  switch (action.type) {
    case 'ADD_TODO':
      console.log('todo ADD_TODO');
      return {
        id: action.id,
        text: action.text,
        completed: false
      };
    case 'TOGGLE_TODO':
      console.log('todo TOGGLE_TODO');
      // Bail out if the action is for a different todo than the one passed in.
      if (state.id !== action.id) {
        return state;
      }

      // ... below is ES7 "Object Rest Destructuring"
      // https://github.com/sebmarkbage/ecmascript-rest-spread/blob/master/Spread.md
      // Think of it as "and the rest", or "override these object properties"
      return _extends({}, state, {
        completed: !state.completed
      });
    default:
      return state;
  }
 };

 ////////////////////////////////////////////////
 //
 // React components
 // (not including generated or root component/s)
 //

 // This is a "stateless component". It gets `props` passed in.
 // https://facebook.github.io/react/blog/2015/09/10/react-v0.14-rc1.html#stateless-function-components
 // Notice the curlybraces in the parameter list. This is destructuring
 // `props` (e.g. filter = props.filter, children = props.children)
 var TodoList = function TodoList(_ref) {
  var todos = _ref.todos;
  var onTodoClick = _ref.onTodoClick;
  return React.createElement(
    'ul',
    null,
    todos.map(function (todo) {
      return React.createElement(Todo, _extends({
        key: todo.id
      }, todo, {
        onClick: function () {
          return onTodoClick(todo.id);
        }
      }));
    })
  );
 };

 var Todo = function Todo(_ref2) {
  var onClick = _ref2.onClick;
  var completed = _ref2.completed;
  var text = _ref2.text;

  return React.createElement(
    'li',
    { onClick: onClick,
      style: { textDecoration: completed ? 'line-through' : 'none' }
    },
    text
  );
 };

 var Link = function Link(_ref3) {
  var active = _ref3.active;
  var children = _ref3.children;
  var onClick = _ref3.onClick;

  if (active) return React.createElement(
    'span',
    null,
    children
  );
  return React.createElement(
    'a',
    { href: '#',
      onClick: function (e) {
        e.preventDefault();
        onClick();
      }
    },
    children
  );
 };

 var Footer = function Footer() {
  return React.createElement(
    'p',
    null,
    'Show:',
    ' ',
    React.createElement(
      FilterLink,
      {
        filter: 'SHOW_ALL' },
      'All'
    ),
    ' ',
    React.createElement(
      FilterLink,
      {
        filter: 'SHOW_ACTIVE' },
      'Active'
    ),
    ' ',
    React.createElement(
      FilterLink,
      { filter: 'SHOW_COMPLETED' },
      'Completed'
    )
  );
 };

 // Intentionally not `const` here.
 // We will override AddTodo later with a connected component.
 var AddTodo = function AddTodo(_ref4) {
  var dispatch = _ref4.dispatch;

  var input = undefined;

  return React.createElement(
    'div',
    null,
    React.createElement('input', { ref: function (node) {
        // This is a newer 0.14 syntax where ref can be a callback.

        // n.b. no `this` available in a functional/stateless component.
        // Here, we're making a closure over `input`, defined above.
        input = node;
      } }),
    React.createElement(
      'button',
      { onClick: function () {
          dispatch(addTodo(input.value));
          input.value = '';
        } },
      'Add todo'
    )
  );
 };

 ////////////////////////////////////////////////
 //
 // react-redux mapping functions
 //

 // This takes Redux state, and returns the props needed
 // for the presentational component.
 var mapStateToTodoListProps = function mapStateToTodoListProps(state) {
  console.log('mapStateToTodoListProps(): state.todos = ' + state.todos);
  return {
    todos: getVisibleTodos(state.todos, state.visibilityFilter)
  };
 };

 // This takes the store's dispatch method, and returns the
 // callbacks props needed for the presentational component.
 var mapDispatchToTodoListProps = function mapDispatchToTodoListProps(dispatch) {
  return {
    onTodoClick: function onTodoClick(id) {
      dispatch(toggleTodo(id));
    }
  };
 };

 var mapStateToFilterLinkProps = function mapStateToFilterLinkProps(state, ownProps) {
  return {
    active: ownProps.filter === state.visibilityFilter
  };
 };

 var mapDispatchToFilterLinkProps = function mapDispatchToFilterLinkProps(dispatch, ownProps) {
  return {
    onClick: function onClick() {
      console.log('FilterLink onClick');
      dispatch(setVisibilityFilter(ownProps.filter));
    }
  };
 };

 ////////////////////////////////////////////////
 //
 // react-redux container components generated by `connect`
 //

 // To create a container component, we use react-redux `connect`.
 // We pass the mapStateToProps and mapDispatchToProps functions
 // defined above.
 //
 // `connect` returns a curried function, which you call on the
 // presentational component. *This* function returns a "connected"
 // or "container" component.
 //
 // What is a connected component anyway?
 //
 // In the mapStateToProps function, we pluck any necessary state
 // from the Redux store, and react-redux wires it to the React props.
 //
 // In the mapDispatchToProps function, we accept a callback to store.dispatch.
 // We return an object, whose keys are callback attributes (`onClick` etc)
 // and whose values are functions that actually perform dispatch.
 //
 // This allows us to take a stateless, dumb, presentation only component,
 // and transform it into a component that knows how to get state from the store,
 // and knows how to dispatch events to the store.
 //
 // The egghead redux video tutorials walk through how to implement `connect`
 // by hand.

 var VisibleTodoList = connect(mapStateToTodoListProps, mapDispatchToTodoListProps)(TodoList);

 var FilterLink = connect(mapStateToFilterLinkProps, mapDispatchToFilterLinkProps)(Link);

 // Default behavior of `connect` (with 0 parameters):
 //   Do not subscribe to any stores, inject `dispatch` as prop.
 // This shorthand is equivalent to AddTodoHardWay, demonstrated below.
 AddTodo = connect()(AddTodo);

 // AddTodoTheHardWay = connect(
 //   state => {
 //     // AddToDo doesn't have any state to be mapped to props.
 //     // Could have just specified null here instead of an anon fn.
 //     return {};
 //   },
 //   dispatch => {
 //     // A bit hard to follow here.
 //     // The 2nd arg of `connect` is the mapDispatchToProps fn.
 //     // This function takes a dispatch function, returns callbacks as needed.
 //     // In other cases, we might return onSomethingClick callbacks here, calling
 //     //  store.dispatch inside those callbacks as necessary.
 //     // In this case, we're just taking dispatch, and returning
 //     //  {dispatch: dispatch}
 //
 //     return { dispatch };
 //   }
 // )(AddTodo);

 ////////////////////////////////////////////////
 //
 // Redux action creators
 //

 // You could just litter the action object boilerplate all throughout
 // the code. This is just DRY/shorthand...
 //
 // ...but it's actually more than that.
 // (?) Closures mean I can keep state
 // (?) Async operations are handled here!

 var nextToDoId = 0; // global :shrug:
 var addTodo = function addTodo(text) {
  return {
    type: 'ADD_TODO',
    id: nextToDoId++,
    text: text
  };
 };

 var setVisibilityFilter = function setVisibilityFilter(filter) {
  return {
    type: 'SET_VISIBILITY_FILTER',
    filter: filter
  };
 };

 var toggleTodo = function toggleTodo(id) {
  return {
    type: 'TOGGLE_TODO',
    id: id
  };
 };

 ////////////////////////////////////////////////
 //
 // Helpers (just a filter, really)
 //

 var getVisibleTodos = function getVisibleTodos(todos, filter) {
  console.log('getVisibleTodos: todos=' + todos + ' filter=' + filter);
  switch (filter) {
    case 'SHOW_ALL':
      return todos;
    case 'SHOW_COMPLETED':
      return todos.filter(function (t) {
        return t.completed;
      });
    case 'SHOW_ACTIVE':
      return todos.filter(function (t) {
        return !t.completed;
      });
  }
 };

 //////////////////////////////////////////////////
 //
 // Root reducer, root component, initial render
 //

 // Top level reducer.
 var todoApp = combineReducers({
  // n.b. following syntax is ES6 Object Initializer (shorthand property names)
  todos: todos, // todos: todos,
  visibilityFilter: visibilityFilter // visibilityFilter: visibilityFilter
 });

 // Create the Redux store from the root reducer.
 var store = createStore(todoApp);

 // Look at how simple the application is now!
 // The top level React component needs no props.
 var TodoApp = function TodoApp() {
  return React.createElement(
    'div',
    null,
    React.createElement(AddTodo, null),
    React.createElement(VisibleTodoList, null),
    React.createElement(Footer, null)
  );
 };

 // react-redux <Provider> uses the React Context feature (`getChildContext`,
 // `childContextTypes`) to inject the store, automatically subscribe and
 // unsubscribe to it at the correct React lifecycle hooks (e.g. `componentDidMount`).
 //
 // See how <Provider> works here:
 // https://github.com/rackt/react-redux/blob/master/src/components/Provider.js

 ReactDOM.render(React.createElement(
  Provider,
  { store: store },
  React.createElement(TodoApp, null)
 ), document.getElementById('root'));
 </script>



 <script id="jsbin-source-javascript" type="text/javascript">/* global ReactRedux, Redux, ReactDOM */

 ////////////////////////////////////////////////
 //
 // Imports
 //

 const { connect, Provider } = ReactRedux;
 const { combineReducers, createStore } = Redux;

 ////////////////////////////////////////////////
 //
 // Reducers (except root, see bottom)
 //

 // 2nd level reducer
 // Here, `state` refers to the array of todo objects
 const todos = (state = [], action) => {
  console.log("todos reducer called");
  switch (action.type) {
    // Returns a new array of todos, containing the added todo as described by `action`.
    // The new todo is constructed by delegating to the `todo` reducer.
    case 'ADD_TODO':
      console.log('todos ADD_TODO');
      // ... below is ES6 "spread operator" (arrays only)
      return [
        ...state,
        todo(undefined, action)
      ];
    // Returns a new array of todos, with an individual todo's completed status
    // toggled as identified by `action.id`.
    // Must operate on entire list (seems wrong somehow).
    case 'TOGGLE_TODO':
      console.log('todos TOGGLE_TODO');
      return state.map(t =>
        todo(t, action)
      );
    default:
      return state;
  }
 };

 // 2nd level reducer
 // Here, `state` refers to a simple configuration string (enum/atom)
 // Remember, we are only returning the state we are concerned with
 const visibilityFilter = (state = 'SHOW_ALL', action) => {
  console.log("visibilityFilter reducer called");
  switch (action.type) {
    case 'SET_VISIBILITY_FILTER':
      return action.filter;
    default:
      return state;
  }
 };

 // 3rd level reducer.
 // Here, `state` refers to a single todo object.
 const todo = (state, action) => {
  console.log("todo reducer called");
  // Remember, no mutation.
  // Initial state is considered (or not, in the ADD_TODO case),
  // and used to construct a new state object, always.

  switch (action.type) {
    case 'ADD_TODO':
      console.log('todo ADD_TODO');
      return {
        id: action.id,
        text: action.text,
        completed: false
      };
    case 'TOGGLE_TODO':
      console.log('todo TOGGLE_TODO');
      // Bail out if the action is for a different todo than the one passed in.
      if (state.id !== action.id) {
        return state;
      }

      // ... below is ES7 "Object Rest Destructuring"
      // https://github.com/sebmarkbage/ecmascript-rest-spread/blob/master/Spread.md
      // Think of it as "and the rest", or "override these object properties"
      return {
        ...state,
        completed: !state.completed
      };
    default:
      return state;
  }
 };

 ////////////////////////////////////////////////
 //
 // React components
 // (not including generated or root component/s)
 //

 // This is a "stateless component". It gets `props` passed in.
 // https://facebook.github.io/react/blog/2015/09/10/react-v0.14-rc1.html#stateless-function-components
 // Notice the curlybraces in the parameter list. This is destructuring
 // `props` (e.g. filter = props.filter, children = props.children)
 const TodoList = ({ todos, onTodoClick }) => (
  <ul>
    {todos.map(todo =>
      <Todo
        key={todo.id}
        {...todo}
        onClick={() => onTodoClick(todo.id)}
      />
    )}
  </ul>
 );


 const Todo = ({ onClick, completed, text }) => {
  return (
    <li onClick={onClick}
      style={{textDecoration: completed ? 'line-through' : 'none'}}
    >
      {text}
    </li>
  );
 };

 const Link = ({ active, children, onClick }) => {
  if (active)
    return <span>{children}</span>;
  return (
    <a href='#'
       onClick={e => {
         e.preventDefault();
         onClick();
       }}
    >
      {children}
    </a>
  );
 };

 const Footer = () => {
  return (
    <p>
      Show:
      {' '}
      <FilterLink
        filter='SHOW_ALL'>All</FilterLink>
      {' '}
      <FilterLink
        filter='SHOW_ACTIVE'>Active</FilterLink>
      {' '}
      <FilterLink filter='SHOW_COMPLETED'>Completed</FilterLink>
    </p>
  );
 };

 // Intentionally not `const` here.
 // We will override AddTodo later with a connected component.
 let AddTodo = ({ dispatch }) => {
  let input;

  return (
    <div>
      <input ref={node => {
        // This is a newer 0.14 syntax where ref can be a callback.

        // n.b. no `this` available in a functional/stateless component.
        // Here, we're making a closure over `input`, defined above.
        input = node;
      }} />
      <button onClick={() => {
        dispatch(addTodo(input.value));
        input.value = '';
      }}>
        Add todo
      </button>
    </div>
  );
 };

 ////////////////////////////////////////////////
 //
 // react-redux mapping functions
 //

 // This takes Redux state, and returns the props needed
 // for the presentational component.
 const mapStateToTodoListProps = (state) => {
  console.log(`mapStateToTodoListProps(): state.todos = ${state.todos}`);
  return {
    todos: getVisibleTodos(
      state.todos,
      state.visibilityFilter
    )
  };
 };

 // This takes the store's dispatch method, and returns the
 // callbacks props needed for the presentational component.
 const mapDispatchToTodoListProps = (dispatch) => {
  return {
    onTodoClick: (id) => {
      dispatch(toggleTodo(id));
    }
  };
 };

 const mapStateToFilterLinkProps = (state, ownProps) => {
  return {
    active: ownProps.filter === state.visibilityFilter
  };
 };

 const mapDispatchToFilterLinkProps = (dispatch, ownProps) => {
  return {
    onClick: () => {
      console.log('FilterLink onClick');
      dispatch(setVisibilityFilter(ownProps.filter));
    }
  };
 };

 ////////////////////////////////////////////////
 //
 // react-redux container components generated by `connect`
 //


 // To create a container component, we use react-redux `connect`.
 // We pass the mapStateToProps and mapDispatchToProps functions
 // defined above.
 //
 // `connect` returns a curried function, which you call on the
 // presentational component. *This* function returns a "connected"
 // or "container" component.
 //
 // What is a connected component anyway?
 //
 // In the mapStateToProps function, we pluck any necessary state
 // from the Redux store, and react-redux wires it to the React props.
 //
 // In the mapDispatchToProps function, we accept a callback to store.dispatch.
 // We return an object, whose keys are callback attributes (`onClick` etc)
 // and whose values are functions that actually perform dispatch.
 //
 // This allows us to take a stateless, dumb, presentation only component,
 // and transform it into a component that knows how to get state from the store,
 // and knows how to dispatch events to the store.
 //
 // The egghead redux video tutorials walk through how to implement `connect`
 // by hand.

 const VisibleTodoList = connect(
  mapStateToTodoListProps, mapDispatchToTodoListProps
 )(TodoList);

 const FilterLink = connect(
  mapStateToFilterLinkProps,
  mapDispatchToFilterLinkProps
 )(Link);

 // Default behavior of `connect` (with 0 parameters):
 //   Do not subscribe to any stores, inject `dispatch` as prop.
 // This shorthand is equivalent to AddTodoHardWay, demonstrated below.
 AddTodo = connect()(AddTodo);

 // AddTodoTheHardWay = connect(
 //   state => {
 //     // AddToDo doesn't have any state to be mapped to props.
 //     // Could have just specified null here instead of an anon fn.
 //     return {};
 //   },
 //   dispatch => {
 //     // A bit hard to follow here.
 //     // The 2nd arg of `connect` is the mapDispatchToProps fn.
 //     // This function takes a dispatch function, returns callbacks as needed.
 //     // In other cases, we might return onSomethingClick callbacks here, calling
 //     //  store.dispatch inside those callbacks as necessary.
 //     // In this case, we're just taking dispatch, and returning
 //     //  {dispatch: dispatch}
 //
 //     return { dispatch };
 //   }
 // )(AddTodo);


 ////////////////////////////////////////////////
 //
 // Redux action creators
 //

 // You could just litter the action object boilerplate all throughout
 // the code. This is just DRY/shorthand...
 //
 // ...but it's actually more than that.
 // (?) Closures mean I can keep state
 // (?) Async operations are handled here!

 let nextToDoId = 0; // global :shrug:
 const addTodo = (text) => {
  return {
    type: 'ADD_TODO',
    id: nextToDoId++,
    text
  };
 };

 const setVisibilityFilter = (filter) => {
  return {
    type: 'SET_VISIBILITY_FILTER',
    filter
  };
 };

 const toggleTodo = (id) => {
  return {
    type: 'TOGGLE_TODO',
    id
  };
 };

 ////////////////////////////////////////////////
 //
 // Helpers (just a filter, really)
 //

 const getVisibleTodos = (todos, filter) => {
  console.log(`getVisibleTodos: todos=${todos} filter=${filter}`);
  switch (filter) {
    case 'SHOW_ALL':
      return todos;
    case 'SHOW_COMPLETED':
      return todos.filter(t => t.completed);
    case 'SHOW_ACTIVE':
      return todos.filter(t => !t.completed);
  }
 };


 //////////////////////////////////////////////////
 //
 // Root reducer, root component, initial render
 //


 // Top level reducer.
 const todoApp = combineReducers({
  // n.b. following syntax is ES6 Object Initializer (shorthand property names)
  todos,              // todos: todos,
  visibilityFilter    // visibilityFilter: visibilityFilter
 });

 // Create the Redux store from the root reducer.
 const store = createStore(todoApp);

 // Look at how simple the application is now!
 // The top level React component needs no props.
 const TodoApp = () => {
  return (
    <div>
      <AddTodo />
      <VisibleTodoList />
      <Footer />
    </div>
  );
 };

 // react-redux <Provider> uses the React Context feature (`getChildContext`,
 // `childContextTypes`) to inject the store, automatically subscribe and
 // unsubscribe to it at the correct React lifecycle hooks (e.g. `componentDidMount`).
 //
 // See how <Provider> works here:
 // https://github.com/rackt/react-redux/blob/master/src/components/Provider.js

 ReactDOM.render(
  <Provider store={store}>
    <TodoApp />
  </Provider>,
  document.getElementById('root')
 );
 </script></body>
 </html>
diff --git a/jsbin.tigakegijo.js b/jsbin.tigakegijo.js
 /* global ReactRedux, Redux, ReactDOM */

 ////////////////////////////////////////////////
 //
 // Imports
 //

 'use strict';

 var _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };

 function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) arr2[i] = arr[i]; return arr2; } else { return Array.from(arr); } }

 var _ReactRedux = ReactRedux;
 var connect = _ReactRedux.connect;
 var Provider = _ReactRedux.Provider;
 var _Redux = Redux;
 var combineReducers = _Redux.combineReducers;
 var createStore = _Redux.createStore;

 ////////////////////////////////////////////////
 //
 // Reducers (except root, see bottom)
 //

 // 2nd level reducer
 // Here, `state` refers to the array of todo objects
 var todos = function todos(state, action) {
  if (state === undefined) state = [];

  console.log("todos reducer called");
  switch (action.type) {
    // Returns a new array of todos, containing the added todo as described by `action`.
    // The new todo is constructed by delegating to the `todo` reducer.
    case 'ADD_TODO':
      console.log('todos ADD_TODO');
      // ... below is ES6 "spread operator" (arrays only)
      return [].concat(_toConsumableArray(state), [todo(undefined, action)]);
    // Returns a new array of todos, with an individual todo's completed status
    // toggled as identified by `action.id`.
    // Must operate on entire list (seems wrong somehow).
    case 'TOGGLE_TODO':
      console.log('todos TOGGLE_TODO');
      return state.map(function (t) {
        return todo(t, action);
      });
    default:
      return state;
  }
 };

 // 2nd level reducer
 // Here, `state` refers to a simple configuration string (enum/atom)
 // Remember, we are only returning the state we are concerned with
 var visibilityFilter = function visibilityFilter(state, action) {
  if (state === undefined) state = 'SHOW_ALL';

  console.log("visibilityFilter reducer called");
  switch (action.type) {
    case 'SET_VISIBILITY_FILTER':
      return action.filter;
    default:
      return state;
  }
 };

 // 3rd level reducer.
 // Here, `state` refers to a single todo object.
 var todo = function todo(state, action) {
  console.log("todo reducer called");
  // Remember, no mutation.
  // Initial state is considered (or not, in the ADD_TODO case),
  // and used to construct a new state object, always.

  switch (action.type) {
    case 'ADD_TODO':
      console.log('todo ADD_TODO');
      return {
        id: action.id,
        text: action.text,
        completed: false
      };
    case 'TOGGLE_TODO':
      console.log('todo TOGGLE_TODO');
      // Bail out if the action is for a different todo than the one passed in.
      if (state.id !== action.id) {
        return state;
      }

      // ... below is ES7 "Object Rest Destructuring"
      // https://github.com/sebmarkbage/ecmascript-rest-spread/blob/master/Spread.md
      // Think of it as "and the rest", or "override these object properties"
      return _extends({}, state, {
        completed: !state.completed
      });
    default:
      return state;
  }
 };

 ////////////////////////////////////////////////
 //
 // React components
 // (not including generated or root component/s)
 //

 // This is a "stateless component". It gets `props` passed in.
 // https://facebook.github.io/react/blog/2015/09/10/react-v0.14-rc1.html#stateless-function-components
 // Notice the curlybraces in the parameter list. This is destructuring
 // `props` (e.g. filter = props.filter, children = props.children)
 var TodoList = function TodoList(_ref) {
  var todos = _ref.todos;
  var onTodoClick = _ref.onTodoClick;
  return React.createElement(
    'ul',
    null,
    todos.map(function (todo) {
      return React.createElement(Todo, _extends({
        key: todo.id
      }, todo, {
        onClick: function () {
          return onTodoClick(todo.id);
        }
      }));
    })
  );
 };

 var Todo = function Todo(_ref2) {
  var onClick = _ref2.onClick;
  var completed = _ref2.completed;
  var text = _ref2.text;

  return React.createElement(
    'li',
    { onClick: onClick,
      style: { textDecoration: completed ? 'line-through' : 'none' }
    },
    text
  );
 };

 var Link = function Link(_ref3) {
  var active = _ref3.active;
  var children = _ref3.children;
  var onClick = _ref3.onClick;

  if (active) return React.createElement(
    'span',
    null,
    children
  );
  return React.createElement(
    'a',
    { href: '#',
      onClick: function (e) {
        e.preventDefault();
        onClick();
      }
    },
    children
  );
 };

 var Footer = function Footer() {
  return React.createElement(
    'p',
    null,
    'Show:',
    ' ',
    React.createElement(
      FilterLink,
      {
        filter: 'SHOW_ALL' },
      'All'
    ),
    ' ',
    React.createElement(
      FilterLink,
      {
        filter: 'SHOW_ACTIVE' },
      'Active'
    ),
    ' ',
    React.createElement(
      FilterLink,
      { filter: 'SHOW_COMPLETED' },
      'Completed'
    )
  );
 };

 // Intentionally not `const` here.
 // We will override AddTodo later with a connected component.
 var AddTodo = function AddTodo(_ref4) {
  var dispatch = _ref4.dispatch;

  var input = undefined;

  return React.createElement(
    'div',
    null,
    React.createElement('input', { ref: function (node) {
        // This is a newer 0.14 syntax where ref can be a callback.

        // n.b. no `this` available in a functional/stateless component.
        // Here, we're making a closure over `input`, defined above.
        input = node;
      } }),
    React.createElement(
      'button',
      { onClick: function () {
          dispatch(addTodo(input.value));
          input.value = '';
        } },
      'Add todo'
    )
  );
 };

 ////////////////////////////////////////////////
 //
 // react-redux mapping functions
 //

 // This takes Redux state, and returns the props needed
 // for the presentational component.
 var mapStateToTodoListProps = function mapStateToTodoListProps(state) {
  console.log('mapStateToTodoListProps(): state.todos = ' + state.todos);
  return {
    todos: getVisibleTodos(state.todos, state.visibilityFilter)
  };
 };

 // This takes the store's dispatch method, and returns the
 // callbacks props needed for the presentational component.
 var mapDispatchToTodoListProps = function mapDispatchToTodoListProps(dispatch) {
  return {
    onTodoClick: function onTodoClick(id) {
      dispatch(toggleTodo(id));
    }
  };
 };

 var mapStateToFilterLinkProps = function mapStateToFilterLinkProps(state, ownProps) {
  return {
    active: ownProps.filter === state.visibilityFilter
  };
 };

 var mapDispatchToFilterLinkProps = function mapDispatchToFilterLinkProps(dispatch, ownProps) {
  return {
    onClick: function onClick() {
      console.log('FilterLink onClick');
      dispatch(setVisibilityFilter(ownProps.filter));
    }
  };
 };

 ////////////////////////////////////////////////
 //
 // react-redux container components generated by `connect`
 //

 // To create a container component, we use react-redux `connect`.
 // We pass the mapStateToProps and mapDispatchToProps functions
 // defined above.
 //
 // `connect` returns a curried function, which you call on the
 // presentational component. *This* function returns a "connected"
 // or "container" component.
 //
 // What is a connected component anyway?
 //
 // In the mapStateToProps function, we pluck any necessary state
 // from the Redux store, and react-redux wires it to the React props.
 //
 // In the mapDispatchToProps function, we accept a callback to store.dispatch.
 // We return an object, whose keys are callback attributes (`onClick` etc)
 // and whose values are functions that actually perform dispatch.
 //
 // This allows us to take a stateless, dumb, presentation only component,
 // and transform it into a component that knows how to get state from the store,
 // and knows how to dispatch events to the store.
 //
 // The egghead redux video tutorials walk through how to implement `connect`
 // by hand.

 var VisibleTodoList = connect(mapStateToTodoListProps, mapDispatchToTodoListProps)(TodoList);

 var FilterLink = connect(mapStateToFilterLinkProps, mapDispatchToFilterLinkProps)(Link);

 // Default behavior of `connect` (with 0 parameters):
 //   Do not subscribe to any stores, inject `dispatch` as prop.
 // This shorthand is equivalent to AddTodoHardWay, demonstrated below.
 AddTodo = connect()(AddTodo);

 // AddTodoTheHardWay = connect(
 //   state => {
 //     // AddToDo doesn't have any state to be mapped to props.
 //     // Could have just specified null here instead of an anon fn.
 //     return {};
 //   },
 //   dispatch => {
 //     // A bit hard to follow here.
 //     // The 2nd arg of `connect` is the mapDispatchToProps fn.
 //     // This function takes a dispatch function, returns callbacks as needed.
 //     // In other cases, we might return onSomethingClick callbacks here, calling
 //     //  store.dispatch inside those callbacks as necessary.
 //     // In this case, we're just taking dispatch, and returning
 //     //  {dispatch: dispatch}
 //
 //     return { dispatch };
 //   }
 // )(AddTodo);

 ////////////////////////////////////////////////
 //
 // Redux action creators
 //

 // You could just litter the action object boilerplate all throughout
 // the code. This is just DRY/shorthand...
 //
 // ...but it's actually more than that.
 // (?) Closures mean I can keep state
 // (?) Async operations are handled here!

 var nextToDoId = 0; // global :shrug:
 var addTodo = function addTodo(text) {
  return {
    type: 'ADD_TODO',
    id: nextToDoId++,
    text: text
  };
 };

 var setVisibilityFilter = function setVisibilityFilter(filter) {
  return {
    type: 'SET_VISIBILITY_FILTER',
    filter: filter
  };
 };

 var toggleTodo = function toggleTodo(id) {
  return {
    type: 'TOGGLE_TODO',
    id: id
  };
 };

 ////////////////////////////////////////////////
 //
 // Helpers (just a filter, really)
 //

 var getVisibleTodos = function getVisibleTodos(todos, filter) {
  console.log('getVisibleTodos: todos=' + todos + ' filter=' + filter);
  switch (filter) {
    case 'SHOW_ALL':
      return todos;
    case 'SHOW_COMPLETED':
      return todos.filter(function (t) {
        return t.completed;
      });
    case 'SHOW_ACTIVE':
      return todos.filter(function (t) {
        return !t.completed;
      });
  }
 };

 //////////////////////////////////////////////////
 //
 // Root reducer, root component, initial render
 //

 // Top level reducer.
 var todoApp = combineReducers({
  // n.b. following syntax is ES6 Object Initializer (shorthand property names)
  todos: todos, // todos: todos,
  visibilityFilter: visibilityFilter // visibilityFilter: visibilityFilter
 });

 // Create the Redux store from the root reducer.
 var store = createStore(todoApp);

 // Look at how simple the application is now!
 // The top level React component needs no props.
 var TodoApp = function TodoApp() {
  return React.createElement(
    'div',
    null,
    React.createElement(AddTodo, null),
    React.createElement(VisibleTodoList, null),
    React.createElement(Footer, null)
  );
 };

 // react-redux <Provider> uses the React Context feature (`getChildContext`,
 // `childContextTypes`) to inject the store, automatically subscribe and
 // unsubscribe to it at the correct React lifecycle hooks (e.g. `componentDidMount`).
 //
 // See how <Provider> works here:
 // https://github.com/rackt/react-redux/blob/master/src/components/Provider.js

 ReactDOM.render(React.createElement(
  Provider,
  { store: store },
  React.createElement(TodoApp, null)
 ), document.getElementById('root'));
	<!DOCTYPE html>
	<html>
	<head>
	<script src="https://fb.me/react-15.3.0.min.js"></script>
	<script src="https://fb.me/react-dom-15.3.0.min.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/redux/3.5.2/redux.min.js"></script>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/react-redux/4.4.5/react-redux.js"></script>
	<meta charset="utf-8">
	<title>JS Bin</title>
	</head>
	<body>
	<div id="root"></div>
	<script id="jsbin-javascript">
	/* global ReactRedux, Redux, ReactDOM */

	////////////////////////////////////////////////
	//
	// Imports
	//

	'use strict';

	var _extends = Object.assign \|\| function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; };

	function _toConsumableArray(arr) { if (Array.isArray(arr)) { for (var i = 0, arr2 = Array(arr.length); i < arr.length; i++) arr2[i] = arr[i]; return arr2; } else { return Array.from(arr); } }

	var _ReactRedux = ReactRedux;
	var connect = _ReactRedux.connect;
	var Provider = _ReactRedux.Provider;
	var _Redux = Redux;
	var combineReducers = _Redux.combineReducers;
	var createStore = _Redux.createStore;

	////////////////////////////////////////////////
	//
	// Reducers (except root, see bottom)
	//

	// 2nd level reducer
	// Here, `state` refers to the array of todo objects
	var todos = function todos(state, action) {
	if (state === undefined) state = [];

	console.log("todos reducer called");
	switch (action.type) {
	// Returns a new array of todos, containing the added todo as described by `action`.
	// The new todo is constructed by delegating to the `todo` reducer.
	case 'ADD_TODO':
	console.log('todos ADD_TODO');
	// ... below is ES6 "spread operator" (arrays only)
	return [].concat(_toConsumableArray(state), [todo(undefined, action)]);
	// Returns a new array of todos, with an individual todo's completed status
	// toggled as identified by `action.id`.
	// Must operate on entire list (seems wrong somehow).
	case 'TOGGLE_TODO':
	console.log('todos TOGGLE_TODO');
	return state.map(function (t) {
	return todo(t, action);
	});
	default:
	return state;
	}
	};

	// 2nd level reducer
	// Here, `state` refers to a simple configuration string (enum/atom)
	// Remember, we are only returning the state we are concerned with
	var visibilityFilter = function visibilityFilter(state, action) {
	if (state === undefined) state = 'SHOW_ALL';

	console.log("visibilityFilter reducer called");
	switch (action.type) {
	case 'SET_VISIBILITY_FILTER':
	return action.filter;
	default:
	return state;
	}
	};

	// 3rd level reducer.
	// Here, `state` refers to a single todo object.
	var todo = function todo(state, action) {
	console.log("todo reducer called");
	// Remember, no mutation.
	// Initial state is considered (or not, in the ADD_TODO case),
	// and used to construct a new state object, always.

	switch (action.type) {
	case 'ADD_TODO':
	console.log('todo ADD_TODO');
	return {
	id: action.id,
	text: action.text,
	completed: false
	};
	case 'TOGGLE_TODO':
	console.log('todo TOGGLE_TODO');
	// Bail out if the action is for a different todo than the one passed in.
	if (state.id !== action.id) {
	return state;
	}

	// ... below is ES7 "Object Rest Destructuring"
	// https://github.com/sebmarkbage/ecmascript-rest-spread/blob/master/Spread.md
	// Think of it as "and the rest", or "override these object properties"
	return _extends({}, state, {
	completed: !state.completed
	});
	default:
	return state;
	}
	};

	////////////////////////////////////////////////
	//
	// React components
	// (not including generated or root component/s)
	//

	// This is a "stateless component". It gets `props` passed in.
	// https://facebook.github.io/react/blog/2015/09/10/react-v0.14-rc1.html#stateless-function-components
	// Notice the curlybraces in the parameter list. This is destructuring
	// `props` (e.g. filter = props.filter, children = props.children)
	var TodoList = function TodoList(_ref) {
	var todos = _ref.todos;
	var onTodoClick = _ref.onTodoClick;
	return React.createElement(
	'ul',
	null,
	todos.map(function (todo) {
	return React.createElement(Todo, _extends({
	key: todo.id
	}, todo, {
	onClick: function () {
	return onTodoClick(todo.id);
	}
	}));
	})
	);
	};

	var Todo = function Todo(_ref2) {
	var onClick = _ref2.onClick;
	var completed = _ref2.completed;
	var text = _ref2.text;

	return React.createElement(
	'li',
	{ onClick: onClick,
	style: { textDecoration: completed ? 'line-through' : 'none' }
	},
	text
	);
	};

	var Link = function Link(_ref3) {
	var active = _ref3.active;
	var children = _ref3.children;
	var onClick = _ref3.onClick;

	if (active) return React.createElement(
	'span',
	null,
	children
	);
	return React.createElement(
	'a',
	{ href: '#',
	onClick: function (e) {
	e.preventDefault();
	onClick();
	}
	},
	children
	);
	};

	var Footer = function Footer() {
	return React.createElement(
	'p',
	null,
	'Show:',
	' ',
	React.createElement(
	FilterLink,
	{
	filter: 'SHOW_ALL' },
	'All'
	),
	' ',
	React.createElement(
	FilterLink,
	{
	filter: 'SHOW_ACTIVE' },
	'Active'
	),
	' ',
	React.createElement(
	FilterLink,
	{ filter: 'SHOW_COMPLETED' },
	'Completed'
	)
	);
	};

	// Intentionally not `const` here.
	// We will override AddTodo later with a connected component.
	var AddTodo = function AddTodo(_ref4) {
	var dispatch = _ref4.dispatch;

	var input = undefined;

	return React.createElement(
	'div',
	null,
	React.createElement('input', { ref: function (node) {
	// This is a newer 0.14 syntax where ref can be a callback.

	// n.b. no `this` available in a functional/stateless component.
	// Here, we're making a closure over `input`, defined above.
	input = node;
	} }),
	React.createElement(
	'button',
	{ onClick: function () {
	dispatch(addTodo(input.value));
	input.value = '';
	} },
	'Add todo'
	)
	);
	};

	////////////////////////////////////////////////
	//
	// react-redux mapping functions
	//

	// This takes Redux state, and returns the props needed
	// for the presentational component.
	var mapStateToTodoListProps = function mapStateToTodoListProps(state) {
	console.log('mapStateToTodoListProps(): state.todos = ' + state.todos);
	return {
	todos: getVisibleTodos(state.todos, state.visibilityFilter)
	};
	};

	// This takes the store's dispatch method, and returns the
	// callbacks props needed for the presentational component.
	var mapDispatchToTodoListProps = function mapDispatchToTodoListProps(dispatch) {
	return {
	onTodoClick: function onTodoClick(id) {
	dispatch(toggleTodo(id));
	}
	};
	};

	var mapStateToFilterLinkProps = function mapStateToFilterLinkProps(state, ownProps) {
	return {
	active: ownProps.filter === state.visibilityFilter
	};
	};

	var mapDispatchToFilterLinkProps = function mapDispatchToFilterLinkProps(dispatch, ownProps) {
	return {
	onClick: function onClick() {
	console.log('FilterLink onClick');
	dispatch(setVisibilityFilter(ownProps.filter));
	}
	};
	};

	////////////////////////////////////////////////
	//
	// react-redux container components generated by `connect`
	//

	// To create a container component, we use react-redux `connect`.
	// We pass the mapStateToProps and mapDispatchToProps functions
	// defined above.
	//
	// `connect` returns a curried function, which you call on the
	// presentational component. This function returns a "connected"
	// or "container" component.
	//
	// What is a connected component anyway?
	//
	// In the mapStateToProps function, we pluck any necessary state
	// from the Redux store, and react-redux wires it to the React props.
	//
	// In the mapDispatchToProps function, we accept a callback to store.dispatch.
	// We return an object, whose keys are callback attributes (`onClick` etc)
	// and whose values are functions that actually perform dispatch.
	//
	// This allows us to take a stateless, dumb, presentation only component,
	// and transform it into a component that knows how to get state from the store,
	// and knows how to dispatch events to the store.
	//
	// The egghead redux video tutorials walk through how to implement `connect`
	// by hand.

	var VisibleTodoList = connect(mapStateToTodoListProps, mapDispatchToTodoListProps)(TodoList);

	var FilterLink = connect(mapStateToFilterLinkProps, mapDispatchToFilterLinkProps)(Link);

	// Default behavior of `connect` (with 0 parameters):
	// Do not subscribe to any stores, inject `dispatch` as prop.
	// This shorthand is equivalent to AddTodoHardWay, demonstrated below.
	AddTodo = connect()(AddTodo);

	// AddTodoTheHardWay = connect(
	// state => {
	// // AddToDo doesn't have any state to be mapped to props.
	// // Could have just specified null here instead of an anon fn.
	// return {};
	// },
	// dispatch => {
	// // A bit hard to follow here.
	// // The 2nd arg of `connect` is the mapDispatchToProps fn.
	// // This function takes a dispatch function, returns callbacks as needed.
	// // In other cases, we might return onSomethingClick callbacks here, calling
	// // store.dispatch inside those callbacks as necessary.
	// // In this case, we're just taking dispatch, and returning
	// // {dispatch: dispatch}
	//
	// return { dispatch };
	// }
	// )(AddTodo);

	////////////////////////////////////////////////
	//
	// Redux action creators
	//

	// You could just litter the action object boilerplate all throughout
	// the code. This is just DRY/shorthand...
	//
	// ...but it's actually more than that.
	// (?) Closures mean I can keep state
	// (?) Async operations are handled here!

	var nextToDoId = 0; // global :shrug:
	var addTodo = function addTodo(text) {
	return {
	type: 'ADD_TODO',
	id: nextToDoId++,
	text: text
	};
	};

	var setVisibilityFilter = function setVisibilityFilter(filter) {
	return {
	type: 'SET_VISIBILITY_FILTER',
	filter: filter
	};
	};

	var toggleTodo = function toggleTodo(id) {
	return {
	type: 'TOGGLE_TODO',
	id: id
	};
	};

	////////////////////////////////////////////////
	//
	// Helpers (just a filter, really)
	//

	var getVisibleTodos = function getVisibleTodos(todos, filter) {
	console.log('getVisibleTodos: todos=' + todos + ' filter=' + filter);
	switch (filter) {
	case 'SHOW_ALL':
	return todos;
	case 'SHOW_COMPLETED':
	return todos.filter(function (t) {
	return t.completed;
	});
	case 'SHOW_ACTIVE':
	return todos.filter(function (t) {
	return !t.completed;
	});
	}
	};

	//////////////////////////////////////////////////
	//
	// Root reducer, root component, initial render
	//

	// Top level reducer.
	var todoApp = combineReducers({
	// n.b. following syntax is ES6 Object Initializer (shorthand property names)
	todos: todos, // todos: todos,
	visibilityFilter: visibilityFilter // visibilityFilter: visibilityFilter
	});

	// Create the Redux store from the root reducer.
	var store = createStore(todoApp);

	// Look at how simple the application is now!
	// The top level React component needs no props.
	var TodoApp = function TodoApp() {
	return React.createElement(
	'div',
	null,
	React.createElement(AddTodo, null),
	React.createElement(VisibleTodoList, null),
	React.createElement(Footer, null)
	);
	};

	// react-redux <Provider> uses the React Context feature (`getChildContext`,
	// `childContextTypes`) to inject the store, automatically subscribe and
	// unsubscribe to it at the correct React lifecycle hooks (e.g. `componentDidMount`).
	//
	// See how <Provider> works here:
	// https://github.com/rackt/react-redux/blob/master/src/components/Provider.js

	ReactDOM.render(React.createElement(
	Provider,
	{ store: store },
	React.createElement(TodoApp, null)
	), document.getElementById('root'));
	</script>



	<script id="jsbin-source-javascript" type="text/javascript">/* global ReactRedux, Redux, ReactDOM */

	////////////////////////////////////////////////
	//
	// Imports
	//

	const { connect, Provider } = ReactRedux;
	const { combineReducers, createStore } = Redux;

	////////////////////////////////////////////////
	//
	// Reducers (except root, see bottom)
	//

	// 2nd level reducer
	// Here, `state` refers to the array of todo objects
	const todos = (state = [], action) => {
	console.log("todos reducer called");
	switch (action.type) {
	// Returns a new array of todos, containing the added todo as described by `action`.
	// The new todo is constructed by delegating to the `todo` reducer.
	case 'ADD_TODO':
	console.log('todos ADD_TODO');
	// ... below is ES6 "spread operator" (arrays only)
	return [
	...state,
	todo(undefined, action)
	];
	// Returns a new array of todos, with an individual todo's completed status
	// toggled as identified by `action.id`.
	// Must operate on entire list (seems wrong somehow).
	case 'TOGGLE_TODO':
	console.log('todos TOGGLE_TODO');
	return state.map(t =>
	todo(t, action)
	);
	default:
	return state;
	}
	};

	// 2nd level reducer
	// Here, `state` refers to a simple configuration string (enum/atom)
	// Remember, we are only returning the state we are concerned with
	const visibilityFilter = (state = 'SHOW_ALL', action) => {
	console.log("visibilityFilter reducer called");
	switch (action.type) {
	case 'SET_VISIBILITY_FILTER':
	return action.filter;
	default:
	return state;
	}
	};

	// 3rd level reducer.
	// Here, `state` refers to a single todo object.
	const todo = (state, action) => {
	console.log("todo reducer called");
	// Remember, no mutation.
	// Initial state is considered (or not, in the ADD_TODO case),
	// and used to construct a new state object, always.

	switch (action.type) {
	case 'ADD_TODO':
	console.log('todo ADD_TODO');
	return {
	id: action.id,
	text: action.text,
	completed: false
	};
	case 'TOGGLE_TODO':
	console.log('todo TOGGLE_TODO');
	// Bail out if the action is for a different todo than the one passed in.
	if (state.id !== action.id) {
	return state;
	}

	// ... below is ES7 "Object Rest Destructuring"
	// https://github.com/sebmarkbage/ecmascript-rest-spread/blob/master/Spread.md
	// Think of it as "and the rest", or "override these object properties"
	return {
	...state,
	completed: !state.completed
	};
	default:
	return state;
	}
	};

	////////////////////////////////////////////////
	//
	// React components
	// (not including generated or root component/s)
	//

	// This is a "stateless component". It gets `props` passed in.
	// https://facebook.github.io/react/blog/2015/09/10/react-v0.14-rc1.html#stateless-function-components
	// Notice the curlybraces in the parameter list. This is destructuring
	// `props` (e.g. filter = props.filter, children = props.children)
	const TodoList = ({ todos, onTodoClick }) => (
	<ul>
	{todos.map(todo =>
	<Todo
	key={todo.id}
	{...todo}
	onClick={() => onTodoClick(todo.id)}
	/>
	)}
	</ul>
	);


	const Todo = ({ onClick, completed, text }) => {
	return (
	<li onClick={onClick}
	style={{textDecoration: completed ? 'line-through' : 'none'}}
	>
	{text}
	</li>
	);
	};

	const Link = ({ active, children, onClick }) => {
	if (active)
	return <span>{children}</span>;
	return (
	<a href='#'
	onClick={e => {
	e.preventDefault();
	onClick();
	}}
	>
	{children}
	</a>
	);
	};

	const Footer = () => {
	return (
	<p>
	Show:
	{' '}
	<FilterLink
	filter='SHOW_ALL'>All</FilterLink>
	{' '}
	<FilterLink
	filter='SHOW_ACTIVE'>Active</FilterLink>
	{' '}
	<FilterLink filter='SHOW_COMPLETED'>Completed</FilterLink>
	</p>
	);
	};

	// Intentionally not `const` here.
	// We will override AddTodo later with a connected component.
	let AddTodo = ({ dispatch }) => {
	let input;

	return (
	<div>
	<input ref={node => {
	// This is a newer 0.14 syntax where ref can be a callback.

	// n.b. no `this` available in a functional/stateless component.
	// Here, we're making a closure over `input`, defined above.
	input = node;
	}} />
	<button onClick={() => {
	dispatch(addTodo(input.value));
	input.value = '';
	}}>
	Add todo
	</button>
	</div>
	);
	};

	////////////////////////////////////////////////
	//
	// react-redux mapping functions
	//

	// This takes Redux state, and returns the props needed
	// for the presentational component.
	const mapStateToTodoListProps = (state) => {
	console.log(`mapStateToTodoListProps(): state.todos = ${state.todos}`);
	return {
	todos: getVisibleTodos(
	state.todos,
	state.visibilityFilter
	)
	};
	};

	// This takes the store's dispatch method, and returns the
	// callbacks props needed for the presentational component.
	const mapDispatchToTodoListProps = (dispatch) => {
	return {
	onTodoClick: (id) => {
	dispatch(toggleTodo(id));
	}
	};
	};

	const mapStateToFilterLinkProps = (state, ownProps) => {
	return {
	active: ownProps.filter === state.visibilityFilter
	};
	};

	const mapDispatchToFilterLinkProps = (dispatch, ownProps) => {
	return {
	onClick: () => {
	console.log('FilterLink onClick');
	dispatch(setVisibilityFilter(ownProps.filter));
	}
	};
	};

	////////////////////////////////////////////////
	//
	// react-redux container components generated by `connect`
	//


	// To create a container component, we use react-redux `connect`.
	// We pass the mapStateToProps and mapDispatchToProps functions
	// defined above.
	//
	// `connect` returns a curried function, which you call on the
	// presentational component. This function returns a "connected"
	// or "container" component.
	//
	// What is a connected component anyway?
	//
	// In the mapStateToProps function, we pluck any necessary state
	// from the Redux store, and react-redux wires it to the React props.
	//
	// In the mapDispatchToProps function, we accept a callback to store.dispatch.
	// We return an object, whose keys are callback attributes (`onClick` etc)
	// and whose values are functions that actually perform dispatch.
	//
	// This allows us to take a stateless, dumb, presentation only component,
	// and transform it into a component that knows how to get state from the store,
	// and knows how to dispatch events to the store.
	//
	// The egghead redux video tutorials walk through how to implement `connect`
	// by hand.

	const VisibleTodoList = connect(
	mapStateToTodoListProps, mapDispatchToTodoListProps
	)(TodoList);

	const FilterLink = connect(
	mapStateToFilterLinkProps,
	mapDispatchToFilterLinkProps
	)(Link);

	// Default behavior of `connect` (with 0 parameters):
	// Do not subscribe to any stores, inject `dispatch` as prop.
	// This shorthand is equivalent to AddTodoHardWay, demonstrated below.
	AddTodo = connect()(AddTodo);

	// AddTodoTheHardWay = connect(
	// state => {
	// // AddToDo doesn't have any state to be mapped to props.
	// // Could have just specified null here instead of an anon fn.
	// return {};
	// },
	// dispatch => {
	// // A bit hard to follow here.
	// // The 2nd arg of `connect` is the mapDispatchToProps fn.
	// // This function takes a dispatch function, returns callbacks as needed.
	// // In other cases, we might return onSomethingClick callbacks here, calling
	// // store.dispatch inside those callbacks as necessary.
	// // In this case, we're just taking dispatch, and returning
	// // {dispatch: dispatch}
	//
	// return { dispatch };
	// }
	// )(AddTodo);


	////////////////////////////////////////////////
	//
	// Redux action creators
	//

	// You could just litter the action object boilerplate all throughout
	// the code. This is just DRY/shorthand...
	//
	// ...but it's actually more than that.
	// (?) Closures mean I can keep state
	// (?) Async operations are handled here!

	let nextToDoId = 0; // global :shrug:
	const addTodo = (text) => {
	return {
	type: 'ADD_TODO',
	id: nextToDoId++,
	text
	};
	};

	const setVisibilityFilter = (filter) => {
	return {
	type: 'SET_VISIBILITY_FILTER',
	filter
	};
	};

	const toggleTodo = (id) => {
	return {
	type: 'TOGGLE_TODO',
	id
	};
	};

	////////////////////////////////////////////////
	//
	// Helpers (just a filter, really)
	//

	const getVisibleTodos = (todos, filter) => {
	console.log(`getVisibleTodos: todos=${todos} filter=${filter}`);
	switch (filter) {
	case 'SHOW_ALL':
	return todos;
	case 'SHOW_COMPLETED':
	return todos.filter(t => t.completed);
	case 'SHOW_ACTIVE':
	return todos.filter(t => !t.completed);
	}
	};


	//////////////////////////////////////////////////
	//
	// Root reducer, root component, initial render
	//


	// Top level reducer.
	const todoApp = combineReducers({
	// n.b. following syntax is ES6 Object Initializer (shorthand property names)
	todos, // todos: todos,
	visibilityFilter // visibilityFilter: visibilityFilter
	});

	// Create the Redux store from the root reducer.
	const store = createStore(todoApp);

	// Look at how simple the application is now!
	// The top level React component needs no props.
	const TodoApp = () => {
	return (
	<div>
	<AddTodo />
	<VisibleTodoList />
	<Footer />
	</div>
	);
	};

	// react-redux <Provider> uses the React Context feature (`getChildContext`,
	// `childContextTypes`) to inject the store, automatically subscribe and
	// unsubscribe to it at the correct React lifecycle hooks (e.g. `componentDidMount`).
	//
	// See how <Provider> works here:
	// https://github.com/rackt/react-redux/blob/master/src/components/Provider.js

	ReactDOM.render(
	<Provider store={store}>
	<TodoApp />
	</Provider>,
	document.getElementById('root')
	);
	</script></body>
	</html>