Require-header NPM

Require-Header

Express middleware to handle errors where an expected header is missing.

Requirements

This library requires the following to run:

Node.js 20+

Usage

Install with npm:

npm install require-header

Load the library into your code with a require call:

const { requireHeader } = require('require-header');

requireHeader will return a middleware function that will error if the request does not set the given header. The error will have message and status properties which you can use.

It accepts two arguments. Firstly, the name of a header which is required:

requireHeader('User-Agent');

Secondly (optionally) a message which will be used in the error if the request message does not match:

requireHeader('User-Agent', 'User-Agent header is required');

Route-level

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

// Only requests with a User-Agent header will continue
app.get(requireHeader('User-Agent'), () => { ... });

If you want to do something useful with the error, for example output a sensible JSON response, you will need to define an error handler for your application (after the route definition):

app.use((error, request, response, next) => {
    response.status(error.status || 500).send({
        message: error.message
    });
});

Application-level

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

// Require a User-Agent header across the entire application
app.use(requireHeader('User-Agent'));

Migration

A new major version of this project is released if breaking changes are introduced. We maintain a migration guide to help users migrate between these versions.