{"id":17711,"library":"ienoopen","title":"IE No Open Middleware","description":"ienoopen is an Express-compatible middleware designed to enhance client-side security by setting the `X-Download-Options` HTTP header to `noopen`. This header, primarily relevant for Internet Explorer 8 and later, prevents users from directly opening downloaded HTML files in the browser's context, thereby mitigating certain types of HTML injection and cross-site scripting (XSS) attacks by forcing a \"Save\" action instead. The package is currently at version 1.1.1, with its last update over six years ago. It is considered to be in maintenance mode, as its standalone GitHub repository is archived, and its functionality has been integrated into the comprehensive `Helmet` security middleware suite, which includes `ienoopen` by default as `helmet.ieNoOpen()`. This package's narrow focus on a single, legacy IE-specific security header is its key differentiator, although its practical relevance has significantly diminished with modern browser adoption.","status":"maintenance","version":"1.1.1","language":"javascript","source_language":"en","source_url":"git://github.com/helmetjs/helmet","tags":["javascript","express","security","x-download-options","typescript"],"install":[{"cmd":"npm install ienoopen","lang":"bash","label":"npm"},{"cmd":"yarn add ienoopen","lang":"bash","label":"yarn"},{"cmd":"pnpm add ienoopen","lang":"bash","label":"pnpm"}],"dependencies":[{"reason":"Runtime dependency for Express.js application middleware integration.","package":"express","optional":false}],"imports":[{"note":"The package exports a default function. Do not use named imports.","wrong":"import { ienoopen } from 'ienoopen';","symbol":"ienoopen","correct":"import ienoopen from 'ienoopen';"},{"note":"CommonJS `require` syntax as shown in the original README.","symbol":"ienoopen","correct":"const ienoopen = require('ienoopen');"},{"note":"The `ienoopen` package ships its own types, but the middleware function itself aligns with Express's `RequestHandler`. No specific types are exported by `ienoopen` beyond its default function.","symbol":"ienoopen.d.ts","correct":"import type { RequestHandler } from 'express';"}],"quickstart":{"code":"import express from 'express';\nimport ienoopen from 'ienoopen';\n\nconst app = express();\nconst port = 3000;\n\n// Apply the ienoopen middleware\n// This sets the 'X-Download-Options: noopen' header\napp.use(ienoopen());\n\napp.get('/', (req, res) => {\n res.send('Hello World! X-Download-Options header set.');\n});\n\napp.get('/download-unsafe-html', (req, res) => {\n res.setHeader('Content-Type', 'text/html');\n res.setHeader('Content-Disposition', 'attachment; filename=\"malicious.html\"');\n // In older IE, without X-Download-Options: noopen, this could be opened directly.\n res.send('

Untrusted content

');\n});\n\napp.listen(port, () => {\n console.log(`Server listening at http://localhost:${port}`);\n console.log('Check response headers for X-Download-Options: noopen on relevant routes.');\n});","lang":"typescript","description":"Sets up an Express server and applies the `ienoopen` middleware to set the `X-Download-Options` header. It also includes an example route that serves a downloadable HTML file to demonstrate the header's purpose in preventing direct execution in IE."},"warnings":[{"fix":"For broader security, consider using a comprehensive security middleware like Helmet, which includes this functionality (as `helmet.ieNoOpen()`) along with other critical headers for modern browsers.","message":"The `X-Download-Options` header, which this package sets, is an unofficial header primarily implemented by Internet Explorer 8+. Modern browsers like Chrome, Firefox, and Safari do not support this header, making its security benefits largely irrelevant for contemporary web development.","severity":"deprecated","affected_versions":">=1.0.0"},{"fix":"Prefer using the `Helmet` middleware suite (`app.use(helmet())` or `app.use(helmet.ieNoOpen())`) if you still require this specific header alongside other modern security protections.","message":"The standalone `ienoopen` package is no longer actively maintained, and its GitHub repository is archived. While functional, no further updates or bug fixes are expected for this standalone module.","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"No direct fix within this package, as it's designed to set a specific, legacy header. Be aware that this header pattern is outdated.","message":"The `X-` prefix for HTTP headers (e.g., `X-Download-Options`) has been deprecated. While still understood by older systems, new headers should avoid this convention.","severity":"gotcha","affected_versions":">=1.0.0"}],"env_vars":null,"last_verified":"2026-04-23T00:00:00.000Z","next_check":"2026-07-22T00:00:00.000Z","problems":[{"fix":"Ensure you call `ienoopen()` to get the middleware function: `app.use(ienoopen());`","cause":"Attempting to use `app.use(ienoopen)` instead of invoking the middleware function `app.use(ienoopen())`.","error":"TypeError: ienoopen is not a function"},{"fix":"Install the package using npm: `npm install ienoopen` or yarn: `yarn add ienoopen`. Double-check the import/require statement for typos.","cause":"The package `ienoopen` has not been installed or there's a typo in the import/require path.","error":"Error: Cannot find module 'ienoopen'"}],"ecosystem":"npm","meta_description":null,"install_score":null,"install_tag":null,"quickstart_score":null,"quickstart_tag":null}