Implement todo API

backend/index.js

@@ -2,11 +2,73 @@ const express = require("express");
 const app = express();
 const PORT = process.env.PORT || 4000;
 
+let todos = [
+];
+let id_counter = 1;
+
+app.use(express.json());
 // Basic route
 app.get("/", (req, res) => {
   res.send("Hello from Express!");
 });
 
+app.get("/api/todos", (req, res) => {
+  res.json(todos);
+});
+
+app.get("/api/todos/:id", (req, res) => {
+  const todoId = parseInt(req.params.id);
+  if (Number.isNaN(todoId)) {
+    return res.status(400).json({ message: "Invalid ID" });
+  }
+  if (!todos.some((todo) => todo.id === todoId)) {
+    return res.status(404).json({ message: "Todo not found" });
+  }
+  res.json(todos.find((todo) => todo.id === todoId));
+});
+
+app.post("/api/todos", (req, res) => {
+  if (!req.body.title) {
+    return res.status(400).json({ message: "Title is required" });
+  }
+  const newTodo = { id: id_counter++, title: req.body.title, completed: false, createdAt: new Date() };
+  todos.push(newTodo);
+  res.status(201).json(newTodo);
+});
+
+app.put("/api/todos/:id", (req, res) => {
+  const todoId = parseInt(req.params.id);
+  if (Number.isNaN(todoId)) {
+    return res.status(400).json({ message: "Invalid ID" });
+  }
+  if (req.body.completed !== undefined && typeof req.body.completed !== "boolean") {
+    return res.status(400).json({ message: "completed must be a boolean" });
+  }
+  const todo = todos.find((t) => t.id === todoId);
+
+  if (todo) {
+    todo.title = req.body.title !== undefined ? req.body.title : todo.title;
+    todo.completed = req.body.completed !== undefined ? req.body.completed : todo.completed;
+    res.json(todo);
+  } else {
+    res.status(404).json({ message: "Todo not found" });
+  }
+});
+
+app.delete("/api/todos/:id", (req, res) => {  
+  const todoId = parseInt(req.params.id);
+  if (Number.isNaN(todoId)) {
+    return res.status(400).json({ message: "Invalid ID" });
+  }
+  const index = todos.findIndex((t) => t.id === todoId);
+  if (index !== -1) {
+    todos.splice(index, 1);
+    return res.status(204).send();
+  } else {
+    res.status(404).json({ message: "Todo not found" });
+  }
+});
+
 // Start server
 app.listen(PORT, () => {
   console.log(`Backend is running on http://localhost:${PORT}`);

backend/package.json

@@ -5,6 +5,6 @@
     "start": "node index.js"
   },
   "dependencies": {
-    "express": "^4.18.2"
+    "express": "^4.22.1"
   }
 }