majorly overhauled 2.8

step2-09/exercise/src/reducers/index.ts

@@ -1,33 +1,21 @@
 import { Store } from '../store';
 import { addTodo, remove, complete, clear, setFilter } from './pureFunctions';
 import { combineReducers } from 'redux';
+import { createReducer } from 'redux-starter-kit';
 
-function todoReducer(state: Store['todos'] = {}, action: any): Store['todos'] {
-  switch (action.type) {
-    case 'addTodo':
-      return addTodo(state, action.id, action.label);
-
-    case 'remove':
-      return remove(state, action.id);
-
-    case 'clear':
-      return clear(state);
-
-    case 'complete':
-      return complete(state, action.id);
+const todoReducer = createReducer<Store['todos']>(
+  {},
+  {
+    addTodo,
+    remove,
+    clear,
+    complete
   }
+);
 
-  return state;
-}
-
-function filterReducer(state: Store['filter'] = 'all', action: any): Store['filter'] {
-  switch (action.type) {
-    case 'setFilter':
-      return setFilter(state, action.filter);
-  }
-
-  return state;
-}
+const filterReducer = createReducer<Store['filter']>('all', {
+  setFilter
+});
 
 export const reducer = combineReducers({
   todos: todoReducer,

step2-09/exercise/src/reducers/pureFunctions.spec.ts

@@ -5,25 +5,19 @@ describe('TodoApp reducers', () => {
   it('can add an item', () => {
     const state = <Store['todos']>{};
 
-    const newState = addTodo(state, '0', 'item1');
+    addTodo(state, { id: '0', label: 'item1' });
 
-    const keys = Object.keys(newState);
-
-    expect(newState).not.toBe(state);
+    const keys = Object.keys(state);
     expect(keys.length).toBe(1);
-    expect(newState[keys[0]].label).toBe('item1');
-    expect(newState[keys[0]].completed).toBeFalsy();
+
+    expect(state['0'].label).toBe('item1');
+    expect(state['0'].completed).toBeFalsy();
   });
 
   it('can complete an item', () => {
     const state = <Store['todos']>{};
-
-    let newState = addTodo(state, '0', 'item1');
-
-    const key = Object.keys(newState)[0];
-
-    newState = complete(newState, key);
-
-    expect(newState[key].completed).toBeTruthy();
+    addTodo(state, { id: '0', label: 'item1' });
+    complete(state, { id: '0' });
+    expect(state['0'].completed).toBeTruthy();
   });
 });

step2-09/exercise/src/reducers/pureFunctions.ts

@@ -1,40 +1,25 @@
-import { Store, FilterTypes } from '../store';
+import { Store } from '../store';
 
-export function addTodo(state: Store['todos'], id: string, label: string): Store['todos'] {
-  return { ...state, [id]: { label, completed: false } };
+export function addTodo(state: Store['todos'], action: any) {
+  state[action.id] = { label: action.label, completed: false };
 }
 
-export function edit(state: Store['todos'], id: string, label: string): Store['todos'] {
-  return { ...state, [id]: { ...state[id], label } };
+export function remove(state: Store['todos'], action: any) {
+  delete state[action.id];
 }
 
-export function remove(state: Store['todos'], id: string) {
-  const newTodos = { ...state };
-
-  delete newTodos[id];
-
-  return newTodos;
-}
-
-export function complete(state: Store['todos'], id: string) {
-  const newTodos = { ...state };
-  newTodos[id].completed = !newTodos[id].completed;
-
-  return newTodos;
+export function complete(state: Store['todos'], action: any) {
+  state[action.id].completed = !state[action.id].completed;
 }
 
 export function clear(state: Store['todos']) {
-  const newTodos = { ...state };
-
   Object.keys(state).forEach(key => {
     if (state[key].completed) {
-      delete newTodos[key];
+      delete state[key];
     }
   });
-
-  return newTodos;
 }
 
-export function setFilter(state: Store['filter'], filter: FilterTypes) {
-  return filter;
+export function setFilter(state: Store['filter'], action: any) {
+  return action.filter;
 }