react app and spring boot

ReactJs and SpringBoot.md

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+# Backend
+
+In SpringInitializer, create a simple SpringBoot RESTfull app to server bad jokes.n Be sure to select SpringWeb component.
+
+*`src/main/java/djmil/cordacheckers/Joke.java`*
+```java
+package djmil.cordacheckers;
+
+public record Joke(String joke) {
+}
+```
+
+*`src/main/java/djmil/cordacheckers/ApiController.java`*
+```java
+package djmil.cordacheckers;
+
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RestController;
+
+@RestController
+public class ApiController {
+    
+    @GetMapping("/api/badjokes")
+    public ResponseEntity<Joke> badJokes() {
+        Joke joke = new Joke("What do you call a fly without wings? A walk!");
+        return ResponseEntity.ok(joke);
+    }
+   
+}
+```
+
+Run backend and check http://localhost:8080/api/badjokes. You should see JSON file with a joke inside.
+
+# Frontend
+
+Now, let's create a React WebApp. It’s super easy to get started with React by using [`create-react-app`](https://facebook.github.io/create-react-app/ "Create React App"). If you have the necessary tools installed (e.g. `node`, `npm`), you can just execute this command
+
+```bash
+npx create-react-app enter-app-name-here
+```
+
+Since we are going host front end app by itself (via node) it does not meter where exactly to place the generated web app. 
+
+*`webapp/src/App.js`*
+```js
+import './App.css';
+import React, { useState, useEffect } from 'react';
+
+function App() {
+
+  const [joke, setJoke] = useState([]);
+  useEffect(() => {
+     fetch('/api/badjokes')
+        .then((response) => response.json())
+        .then((data) => {
+           console.log(data.joke);
+           setJoke(data.joke);
+        })
+        .catch((err) => {
+           console.log(err.message);
+        });
+  }, []);
+
+  return (
+    <div className="App">
+      <header className="App-header">
+        <p>         
+          Here is your joke: {joke}
+        </p>
+      </header>
+    </div>
+  );
+}
+
+export default App;
+```
+
+Run the app with `npm start` command
+
+## Proxy
+
+By default React uses 3000 port. And all REST requests would fail, because SpringBoot serves on 8080. To fix this issue in your dev environment, add this line to the `package.json`
+
+```json
+"proxy": "http://localhost:8080",
+```
+
+This will configure underline server to redirect (proxy) all requests to specified domain. More [granular configuration](https://create-react-app.dev/docs/proxying-api-requests-in-development/) is also possible.