app.mountpath Property

app.mountpath contains the path pattern(s) on which a sub-application is mounted.

Syntax

app.mountpath

Example

const express = require("express");
const app = express();
const adminApp = express();
const PORT = 4900;

adminApp.get("/", (req, res) => {
    console.log(adminApp.mountpath); // /admin
    res.send("Admin sub-app home");
});

app.use("/admin", adminApp);

app.listen(PORT, () => console.log(`Listening on ${PORT}`));

Multiple mount paths

app.use(["/admin", "/backoffice"], adminApp);

Here, adminApp.mountpath becomes ["/admin", "/backoffice"].

Use cases

Identifying where a sub-application is mounted.
Debugging apps composed of multiple sub-applications.
Supporting a sub-app mounted on more than one path.