req.query

req.query gives you access to everything after the ? in a URL — the query-string parameters.

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

app.get("/search", (req, res) => {
    console.log(req.query.keyword);
    res.send(`Searching for: ${req.query.keyword}`);
});

app.listen(4600, () => console.log("Listening on 4600"));

A request to /search?keyword=react populates req.query.keyword with "react".

Common uses

• Filtering and searching resources.
• Sorting results.
• Pagination (?page=2&limit=10).
• Passing optional flags to an endpoint.