new batch of redux challenge hints and solutions (#19691)

guide/english/certifications/front-end-libraries/redux/send-action-data-to-the-store/index.md

@@ -3,8 +3,44 @@ title: Send Action Data to the Store
 ---
 ## Send Action Data to the Store
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/front-end-libraries/redux/send-action-data-to-the-store/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
+### Hint 1
+Remember that in Redux, action creator functions return action objects. Objects can hold multiple values. The action object in ```addNoteText``` should contain both type and text variables. Figure out the corresponding value to pass for each of the variables in the object. 
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+### Hint 2
+In the ```notesReducer``` function, create a case condition that checks for the ```type``` of action and returns the value of ```text``` from the ```addNoteText``` function.
 
+### Solution
+```javascript
+const ADD_NOTE = 'ADD_NOTE';
+
+const notesReducer = (state = 'Initial State', action) => {
+  switch(action.type) {
+    // change code below this line
+
+    case ADD_NOTE:
+      return action.text;
+      
+    // change code above this line
+    default:
+      return state;
+  }
+};
+
+const addNoteText = (note) => {
+  // change code below this line
+
+  return {
+    type: ADD_NOTE,
+    text: note
+  }
+
+  // change code above this line
+};
+
+const store = Redux.createStore(notesReducer);
+
+console.log(store.getState());
+store.dispatch(addNoteText('Hello!'));
+console.log(store.getState());
+```
 <!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->

guide/english/certifications/front-end-libraries/redux/use-middleware-to-handle-asynchronous-actions/index.md

@@ -3,8 +3,71 @@ title: Use Middleware to Handle Asynchronous Actions
 ---
 ## Use Middleware to Handle Asynchronous Actions
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/front-end-libraries/redux/use-middleware-to-handle-asynchronous-actions/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
+### Hint 1
+Treat the ```dispatch``` argument as a function and pass the action events in it. 
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+### Hint 2
+The ```requestingData``` action event will be passed first. 
 
+### Hint 3
+The ```receivedData``` action event will be passed after the ```setTimeout``` function. 
+
+This sequence simulates the process of requesting the data, receiving the data and then dispatching the received data. 
+
+### Hint 4
+It is important that the ```data``` variable be passed as an argument of ```receivedData```. 
+
+### Solution
+```javascript
+const REQUESTING_DATA = 'REQUESTING_DATA'
+const RECEIVED_DATA = 'RECEIVED_DATA'
+
+const requestingData = () => { return {type: REQUESTING_DATA} }
+const receivedData = (data) => { return {type: RECEIVED_DATA, users: data.users} }
+
+const handleAsync = () => {
+  return function(dispatch) {
+    // dispatch request action here
+
+    dispatch(requestingData());
+
+    setTimeout(function() {
+      let data = {
+        users: ['Jeff', 'William', 'Alice']
+      }
+      // dispatch received data action here
+
+      dispatch(receivedData(data));
+
+    }, 2500);
+  }
+};
+
+const defaultState = {
+  fetching: false,
+  users: []
+};
+
+const asyncDataReducer = (state = defaultState, action) => {
+  switch(action.type) {
+    case REQUESTING_DATA:
+      return {
+        fetching: true,
+        users: []
+      }
+    case RECEIVED_DATA:
+      return {
+        fetching: false,
+        users: action.users
+      }
+    default:
+      return state;
+  }
+};
+
+const store = Redux.createStore(
+  asyncDataReducer,
+  Redux.applyMiddleware(ReduxThunk.default)
+);
+```
 <!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->

guide/english/certifications/front-end-libraries/redux/write-a-counter-with-redux/index.md

@@ -3,8 +3,50 @@ title: Write a Counter with Redux
 ---
 ## Write a Counter with Redux
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/certifications/front-end-libraries/redux/write-a-counter-with-redux/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
+The goal of this challenge is to apply all the concepts learned from previous Redux challenges and create a simple counter that will increment or decrement a state by 1. 
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+### Hint 1
+The best way to solve this challenge is by reviewing previous redux lessons particularly the following:
+- [Use const for Action Types](https://learn.freecodecamp.org/front-end-libraries/redux/use-const-for-action-types/)
+- [Use a Switch Statement to Handle Multiple Actions](https://learn.freecodecamp.org/front-end-libraries/redux/use-a-switch-statement-to-handle-multiple-actions/)
+- [Define an Action Creator](https://learn.freecodecamp.org/front-end-libraries/redux/define-an-action-creator/)
+- [Handle an Action in the Store](https://learn.freecodecamp.org/front-end-libraries/redux/handle-an-action-in-the-store/)
+- [Create a Redux Store](https://learn.freecodecamp.org/front-end-libraries/redux/create-a-redux-store)
 
+### Solution
+```javascript
+const INCREMENT = 'INCREMENT'; // define a constant for increment action types
+const DECREMENT = 'DECREMENT'; // define a constant for decrement action types
+
+// define the counter reducer which will increment or decrement the state based on the action it receives
+const counterReducer = (state = 0, action) => {
+    switch(action.type){
+        case INCREMENT: 
+            return state+=1;          
+
+        case DECREMENT: 
+            return state-=1;                
+            
+        default:
+            return state;
+    }
+} ; 
+
+// define an action creator for incrementing
+const incAction = () => { 
+    return {
+        type: INCREMENT
+    }
+}; 
+
+// define an action creator for decrementing
+const decAction = () => { 
+    return {
+        type: DECREMENT
+    }
+}; 
+
+// define the Redux store here, passing in your reducers
+const store = Redux.createStore(counterReducer); 
+```
 <!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->