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Query strings

Search (query string) parameters can be accessed in the req.query object, which implements the URLSearchParams interface.

Get the value of a search parameter

Use req.query.get(key) to get the first value associated with a given search parameter. If you need to check whether a parameter is set, use *.query.has(name):

router.get("/page", (req, res) => {
if (req.query.has("id")) {
res.send(`Your page id is: ${req.query.get("id")}`)
} else {
res.send("No id! Add one like this: /page?id=123")

💡 You can use req.query.getAll(key) to get all the values of query string array.

Listing search parameters

Use req.query.entries() method to iterate through all key/value pairs in the same order as they appear in the query string.

for (const [key, value] of req.query.entries()) {
console.log(`Query parameter: ${key}`, value);

If you need only the keys or values, use req.query.keys() or req.query.values(), respectively.

Manipulating query strings

req.query is a URLSearchParams object. You can use a bunch of utility methods to work with query parameters:

  • req.query.set(name, value) sets the value of a given search parameter.
  • req.query.append(name, value) appends a new search parameter.
  • req.query.delete(name) removes a search parameter and its value(s).
  • req.query.sort() sorts all query string parameters by name.
  • req.query.toString() returns a serialized query string suitable for use in a URL.