Gluing together the frontend and backend

backend/cmd/main.go

@@ -12,15 +12,18 @@ import (
 
 // The button state as represented in memory
 type ButtonState struct {
-	pressCount int
+	PressCount int `json:"pressCount"`
 }
 
 // This is what a handler with a receiver looks like
 // Keep in mind that concurrent state access is not (usually) safe
 // And will in pracice be guarded by a mutex
 func (b *ButtonState) pressHandler(w http.ResponseWriter, r *http.Request) {
-	b.pressCount++
-	response, err := json.Marshal(b.pressCount)
+	if r.Method != "POST" {
+		b.PressCount++
+	}
+
+	response, err := json.Marshal(b)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -38,13 +41,13 @@ func handler(w http.ResponseWriter, r *http.Request) {
 
 func main() {
 	database.DbConnect()
-	b := &ButtonState{pressCount: 0}
+	b := &ButtonState{PressCount: 0}
 
 	// Mounting the handlers
 	fs := http.FileServer(http.Dir("static"))
 	http.Handle("/", fs)
 	http.HandleFunc("/hello", handler)
-	http.HandleFunc("/button", b.pressHandler)
+	http.HandleFunc("/api/button", b.pressHandler)
 
 	// Start the server on port 8080
 	println("Currently listening on http://localhost:8080")

frontend/src/App.tsx

@@ -1,11 +1,9 @@
-import { useState } from "react";
 import reactLogo from "./assets/react.svg";
 import viteLogo from "/vite.svg";
 import "./App.css";
+import { CountButton } from "./Components/CountButton";
 
 function App(): JSX.Element {
-  const [count, setCount] = useState(0);
-
   return (
     <>
       <div>
@@ -18,13 +16,7 @@ function App(): JSX.Element {
       </div>
       <h1>Vite + React</h1>
       <div className="card">
-        <button
-          onClick={() => {
-            setCount((count): number => count + 1);
-          }}
-        >
-          count is {count}
-        </button>
+        <CountButton />
         <p>
           Edit <code>src/App.tsx</code> and save to test HMR
         </p>

frontend/src/Components/CountButton.tsx

@@ -0,0 +1,39 @@
+import { useState, useEffect } from "react";
+
+// Interface for the response from the server
+// This should eventually reside in a dedicated file
+interface CountResponse {
+  pressCount: number;
+}
+
+// Some constants for the button
+const BUTTON_ENDPOINT = "/api/button";
+
+// A simple button that counts how many times it's been pressed
+export function CountButton(): JSX.Element {
+  const [count, setCount] = useState<number>(NaN);
+
+  // useEffect with a [] dependency array runs only once
+  useEffect(() => {
+    async function getCount(): Promise<void> {
+      const response = await fetch(BUTTON_ENDPOINT);
+      const data = (await response.json()) as CountResponse;
+      setCount(data.pressCount);
+    }
+    void getCount();
+  }, []);
+
+  // This is what runs on every button click
+  function press(): void {
+    async function pressPost(): Promise<void> {
+      await fetch(BUTTON_ENDPOINT, { method: "POST" });
+      const response = await fetch(BUTTON_ENDPOINT);
+      const data = (await response.json()) as CountResponse;
+      setCount(data.pressCount);
+    }
+    void pressPost();
+  }
+
+  // Return some JSX with the button and associated handler
+  return <button onClick={press}>count is {count}</button>;
+}

frontend/vite.config.ts

@@ -4,4 +4,19 @@ import react from "@vitejs/plugin-react-swc";
 // https://vitejs.dev/config/
 export default defineConfig({
   plugins: [react()],
+  // build: {
+  //   outDir: '../server/public' // Override default outDir('dist')
+  // },
+  server: {
+    port: 3000,
+    open: true,
+    proxy: {
+      "/api": {
+        target: "http://localhost:8080/api",
+        changeOrigin: true,
+        secure: false,
+        rewrite: (path): string => path.replace(/^\/api/, ""),
+      },
+    },
+  },
 });