How to get GET (query string) variables in Express.js on Node.js?

When building an Express.js application, you can access query string parameters (i.e., variables appended in the URL after the ? symbol) via req.query inside your route handlers. Below is a concise guide on how to do it.

1. Basic Usage

If you have a URL like:

GET /search?term=nodejs&page=2

You can read the query parameters in your route like this:

app.get('/search', (req, res) => {
  const term = req.query.term;  // "nodejs"
  const page = req.query.page;  // "2"

  // Do something with 'term' or 'page'
  res.send(`You searched for "${term}" on page ${page}`);
});

The req.query object automatically parses any key-value pairs in the query string and makes them accessible as properties.

2. Default / Fallback Values

If the URL doesn’t include certain query parameters, req.query will simply not have those properties. You can provide defaults or handle missing values:

app.get('/search', (req, res) => {
  const term = req.query.term || 'defaultTerm';
  const page = req.query.page || 1;
  // ...
});

3. Complex or Nested Query Parameters

By default, Express parses query parameters as simple key-value pairs. For example:

GET /users?role=admin&role=moderator

The result might be req.query.role = 'moderator', or 'admin' if you are using default Express query parsing without additional libraries.

If you need nested query structures or arrays, consider using a parsing library like qs, or configure Express to use a custom query parser. That said, for most use cases, the default req.query is enough.

4. Example With All Steps

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

app.get('/search', (req, res) => {
  // req.query is an object containing all query string parameters
  const { term, page } = req.query;

  // Provide defaults
  const searchTerm = term || 'nodejs';
  const currentPage = page || 1;

  res.json({
    searchTerm,
    currentPage
  });
});

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

Now, if you visit:

http://localhost:3000/search?term=express&page=2

You’ll receive a JSON response like:

{
  "searchTerm": "express",
  "currentPage": "2"
}

Recommended Resources

Grokking JavaScript Fundamentals

Conclusion

To get GET (query) parameters in an Express.js application, reference req.query in your route handlers. This provides you an object containing all the key-value pairs from the URL query string. If you need more advanced parsing (e.g., nested objects), configure a custom query parser or use a library like qs.

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