Perutean & Middleware dalam Express
Kuasai perutean Express untuk mendefinisikan titik akhir API dan menerapkan middleware untuk pemrosesan permintaan.
Perutean & Middleware dalam Express adalah pelajaran Node.js Backend Development Bootcamp gratis di CoddyKit. Ini adalah pelajaran 2 dari 4. Kamu bisa membaca pelajaran lengkapnya di bawah secara gratis — lalu praktikkan langsung di browser dengan editor kode bawaan dan tutor AI 24/7. Ini adalah bagian dari jalur belajar Node.js Backend Development Bootcamp, dan progresmu tersinkronisasi di web dan aplikasi CoddyKit. Kursus Node.js Backend Development Bootcamp mencakup 4 pelajaran total.
Bagian dari pelajaran ini belum diterjemahkan dan ditampilkan dalam bahasa Inggris.
Routing Your Express API
Welcome back! In this lesson, we'll dive into routing and middleware in Express. These are core concepts for building powerful and organized web applications.
Routing helps your server understand what to do when it receives different requests, like showing a user profile or saving new data.
Defining Basic Routes
A route tells your Express app how to respond to a specific type of request to a particular URL path. You define routes using methods like app.get(), app.post(), app.put(), and app.delete().
Each route method takes a path and a handler function that executes when the route is matched.
First GET Route Example
Let's create a simple GET route that responds to requests at the root URL (/). This is often your homepage or a basic API status check.
The handler function receives req (request) and res (response) objects.
const express = require('express');
const app = express();
const port = 3000;
app.get('/', (req, res) => {
res.send('Hello from our Express API!');
});
app.listen(port, () => {
console.log(`Server running on http://localhost:${port}`);
});Handling Dynamic Route Parameters
Often, you need to capture dynamic values from the URL, like a user's ID. This is done with route parameters, denoted by a colon (:) in the path.
You can access these parameters through the req.params object in your route handler.
const express = require('express');
const app = express();
const port = 3000;
app.get('/users/:userId', (req, res) => {
const userId = req.params.userId;
res.send(`You requested user ID: ${userId}`);
});
app.listen(port, () => {
console.log(`Server running on http://localhost:${port}`);
});What is Middleware?
Middleware functions are functions that have access to the request object (req), the response object (res), and the next middleware function in the application’s request-response cycle.
They can:
- Execute any code.
- Make changes to the request and the response objects.
- End the request-response cycle.
- Call the next middleware function in the stack.
The 'next()' Function
The key to middleware is the next() function. If a middleware function does not end the request-response cycle (e.g., by calling res.send()), it must call next() to pass control to the next middleware function or route handler.
If next() is not called, the request will be left hanging.
Application-level Middleware
You can apply middleware globally to all requests using app.use(). This is great for tasks like logging, parsing JSON bodies, or setting common headers.
Let's create a simple logger that runs for every incoming request.
const express = require('express');
const app = express();
const port = 3000;
// Application-level middleware
app.use((req, res, next) => {
console.log(`[${new Date().toISOString()}] ${req.method} ${req.url}`);
next(); // Don't forget to call next()
});
app.get('/', (req, res) => {
res.send('Check your server console for the log!');
});
app.listen(port, () => {
console.log(`Server running on http://localhost:${port}`);
});Route-level Middleware
Sometimes, you only want middleware to run for specific routes. You can apply route-level middleware by passing it as an argument before the route handler function.
You can even chain multiple middleware functions for a single route.
const express = require('express');
const app = express();
const port = 3000;
// A simple authentication middleware
const isAuthenticated = (req, res, next) => {
if (req.headers.authorization === 'Bearer mysecrettoken') {
next(); // User is authenticated, proceed
} else {
res.status(401).send('Unauthorized: Invalid token');
}
};
// Apply isAuthenticated middleware only to this route
app.get('/dashboard', isAuthenticated, (req, res) => {
res.send('Welcome to the protected dashboard!');
});
app.get('/', (req, res) => {
res.send('Public content here.');
});
app.listen(port, () => {
console.log(`Server running on http://localhost:${port}`);
});Common Middleware Uses
Middleware is incredibly versatile. Here are some common use cases:
- Authentication/Authorization: Checking user credentials or permissions.
- Logging: Recording request details for debugging or monitoring.
- Body Parsing: Extracting JSON or URL-encoded data from request bodies (e.g.,
express.json()). - Error Handling: Catching and responding to errors (special middleware type).
- Input Validation: Ensuring request data meets specific criteria.
Middleware & Routing Check
Let's test your understanding of Express routing and middleware!
Recap: Routing & Middleware
Great job! You've learned how Express uses routing to direct requests to specific handlers based on URL paths and HTTP methods.
You also mastered middleware, powerful functions that can intercept and process requests at various stages, either globally with app.use() or for specific routes. Understanding these concepts is fundamental to building robust Express applications!
Pertanyaan yang Sering Diajukan
Apakah pelajaran “Perutean & Middleware dalam Express” gratis?
Ya — teks lengkap “Perutean & Middleware dalam Express” gratis dibaca di sini di web. Untuk praktiknya secara interaktif (editor kode bawaan dan tutor AI 24/7) dan buka sisa kursus Node.js Backend Development Bootcamp, upgrade ke CoddyKit PRO. Kursus Node.js Backend Development Bootcamp mencakup 4 pelajaran total.
Apa yang akan aku pelajari di “Perutean & Middleware dalam Express”?
Kuasai perutean Express untuk mendefinisikan titik akhir API dan menerapkan middleware untuk pemrosesan permintaan. Kamu berlatih Node.js Backend Development Bootcamp dengan kode praktik yang langsung kamu jalankan di browser, dan tutor AI 24/7 menjawab pertanyaanmu saat kamu mengerjakan pelajaran ini.
Apakah aku perlu pengalaman untuk memulai Node.js Backend Development Bootcamp?
Tidak diperlukan pengalaman sebelumnya. Node.js Backend Development Bootcamp di CoddyKit dirancang untuk pemula hingga pelajar tingkat lanjut, jadi kamu bisa memulai di sini atau dari awal dan belajar sesuai kecepatan kamu sendiri. Ini adalah pelajaran 2 dari 4.
Berapa lama pelajaran “Perutean & Middleware dalam Express” memakan waktu?
Sebagian besar pelajaran CoddyKit memakan waktu sekitar 5–10 menit. Setiap pelajaran ringkas dan interaktif, jadi kamu membuat kemajuan stabil dan melanjutkan dari tempat kamu tinggalkan di web dan aplikasi.
Bisakah aku menulis dan menjalankan kode dalam pelajaran Node.js Backend Development Bootcamp ini?
Ya. Setiap pelajaran Node.js Backend Development Bootcamp menyertakan editor kode bawaan, jadi kamu menulis dan menjalankan kode nyata langsung di browser dan mendapatkan umpan balik AI instan — tidak diperlukan penyiapan lokal.
Semua pelajaran dalam kursus ini
- Dasar-Dasar Kerangka Kerja Express.js
- Perutean & Middleware dalam Express
- Merancang Titik Akhir API Bergaya REST
- Menangani Data Permintaan: Body, Query & Parameter