How to Get Query String Variables in Express.js on Node.js?

To get query string variables in Express.js on Node.js, we can use the req.query property.

For instance, we can write:

const express = require('express')
const app = express()
const port = 3000

app.get('/', (req, res) => {
  res.json(req.query)
})

app.listen(port, () => {
  console.log(`Example app listening at http://localhost:${port}`)
})

to return the req.query object as the response in the / route.

Then when we add ?foo=bar at the of the URL as the query string, we should see:

{
  "foo": "bar"
}

returned as the response.