res.send() | DevNotes

res.send() sends a response of virtually any type — a string, object, array, or Buffer — and sets the Content-Type header automatically.

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

app.get("/ping", (req, res) => {
    res.send("pong");
});

app.get("/info", (req, res) => {
    res.send({ service: "Order Service", status: "healthy" });
});

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

Common uses

Sending plain-text acknowledgements.
Returning small JSON payloads without calling res.json() explicitly.
Sending rendered HTML fragments.