Express

Supports Express ^4.18.0 || ^5.0.0.

Import undevice from undevice/express and register app.use(undevice()) before your routes. Each request gets a fresh frozen result in res.locals.undevice. Importing the adapter automatically types built-in flags in route handlers.

Setup

import express from 'express';
import { undevice } from 'undevice/express';

const app = express();
app.use(undevice());

app.get('/device', (_req, res) => {
  res.locals.undevice.isMobile; // boolean
  res.json(res.locals.undevice);
});

Custom flag types

Extend UndeviceCustomFlags to type custom flags in Express routes.

Manual declarations

Declare custom flag names with the type boolean. Include only flags passed to the middleware configuration:

undevice.d.ts

import 'undevice/express';

declare module 'undevice/express' {
  interface UndeviceCustomFlags {
    isCustomFlag: boolean;
    isAnotherCustomFlag: boolean;
  }
}

Inference from middleware

UndeviceMiddlewareFlags<typeof undeviceMiddleware> extracts custom flag types from the configured middleware:

app.ts

import express from 'express';
import { undevice } from 'undevice/express';

const app = express();
export const undeviceMiddleware = undevice({
  isBot: ['bot'],
  isRawClient: ['curl', 'wget'],
});

app.use(undeviceMiddleware);

app.get('/device', (_req, res) => {
  res.locals.undevice.isMobile;    // boolean
  res.locals.undevice.isBot;       // boolean
  res.locals.undevice.isRawClient; // boolean
  res.json(res.locals.undevice);
});

undevice.d.ts

import type { UndeviceMiddlewareFlags } from 'undevice/express';
import type { undeviceMiddleware } from './app.js';

type Flags = UndeviceMiddlewareFlags<typeof undeviceMiddleware>;

declare module 'undevice/express' {
  interface UndeviceCustomFlags extends Flags {}
}

Include undevice.d.ts in the application's TypeScript project. The augmentation applies to all Express routes in that project.