Express.js Handling GET Requests

GET requests are one of the most common types of HTTP requests. In Express, you can handle GET requests by defining route handlers for specific paths. This allows you to fetch data from the server and return it to the client in various formats such as HTML, JSON, or plain text.

 

Key Features of Handling GET Requests

• Request Handling: You can handle GET requests to retrieve resources.
• Path Parameters: You can define dynamic paths using parameters.
• Query Strings: You can access and handle query parameters from the request URL.
• HTTP Methods: GET is used primarily for retrieving data, making it a safe operation.

 

Handling Basic GET Requests

You can use the app.get() method to define a route handler for a GET request. It takes the path and a callback function that handles the request and sends a response.

Example:

const express = require('express');
const app = express();

// Handle GET request to the root path
app.get('/', (req, res) => {
    res.send('Hello, World!');
});

// Start the server
app.listen(3000, () => {
    console.log('Server running on port 3000');
});

 

Handling GET Requests with Path Parameters

You can define dynamic routes with path parameters. This allows you to capture variable parts of the URL and use them in your handler.

Example:

app.get('/user/:id', (req, res) => {
    const userId = req.params.id;  // Extracting parameter from the URL
    res.send(`User ID: ${userId}`);
});

In the above example, a request to /user/123 will send User ID: 123 as the response.

 

Handling GET Requests with Query Strings

Query strings are often used to pass additional information in the URL after a ? symbol. You can access query parameters using req.query.

Example:

app.get('/search', (req, res) => {
    const query = req.query.q;  // Extracting query parameter 'q'
    res.send(`Search results for: ${query}`);
});

A request to /search?q=expressjs will return Search results for: expressjs.

 

Example of Handling GET Requests with Both Parameters and Query Strings

app.get('/product/:id', (req, res) => {
    const productId = req.params.id;
    const category = req.query.category;  // Accessing query string
    
    res.send(`Product ID: ${productId}, Category: ${category}`);
});

For a request to /product/101?category=electronics, the response would be Product ID: 101, Category: electronics.

 

Handling GET Requests with a Callback Function

When handling GET requests, you can define a callback function that processes the request and sends the appropriate response.

Example:

app.get('/welcome', (req, res) => {
    res.json({ message: 'Welcome to the Express application!' });
});

This sends a JSON response when the /welcome route is accessed.

 

Example of Handling Multiple GET Requests

You can define multiple GET route handlers for different paths or conditions.

Example:

app.get('/', (req, res) => {
    res.send('Home Page');
});

app.get('/about', (req, res) => {
    res.send('About Page');
});

In this case, the server responds with different content based on the requested URL.

 

Summary

Handling GET requests in Express.js allows you to define endpoints for fetching data from your application. You can handle simple GET requests, as well as more complex requests that include dynamic path parameters and query strings. Using the app.get() method, you can respond with various types of data, such as plain text, HTML, or JSON. This flexibility makes Express a powerful tool for building web APIs and serving data.