URL params and query params

URL Parameters:

URL parameters are values included in the URL itself, typically denoted by a colon followed by the parameter name in Express. They are used to extract specific information from the URL.

Explanation:

In a URL like http://example.com/users/:userId, :userId is a URL parameter. When a user accesses a URL like http://example.com/users/123, you can extract the value 123 as the userId parameter.

Implementation in Express:

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

// Define a route with a URL parameter
app.get('/users/:userId', (req, res) => {
  const userId = req.params.userId;
  res.send(`User ID: ${userId}`);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

In this example, when a user accesses /users/123, the userId parameter is extracted, and the response will be "User ID: 123".

Query Parameters:

Query parameters are additional key-value pairs in the URL following a question mark (?). They are used to send data to the server via the URL.

Explanation:

In a URL like http://example.com/search?query=Node&category=Tutorials, query and category are query parameters. They allow users to specify search terms or filter results.

Implementation in Express:

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

// Define a route that handles query parameters
app.get('/search', (req, res) => {
  const query = req.query.query;
  const category = req.query.category;
  res.send(`Search Query: ${query}, Category: ${category}`);
});

app.listen(3000, () => {
  console.log('Server is running on port 3000');
});

In this example, when a user accesses /search?query=Node&category=Tutorials, the query parameters query and category are extracted, and the response will be "Search Query: Node, Category: Tutorials".

You can test these examples by running the code and accessing the specified URLs in your browser or using tools like Postman.