{"id":17461,"library":"polkadot-middleware","title":"Polkadot Middleware","description":"The `polkadot-middleware` package provides a familiar middleware pattern for the `polkadot` HTTP server, streamlining request handler composition. Currently at version 1.0.1, it offers a functional alternative to manual function nesting, simplifying the development of server-side logic. This library addresses the current lack of a native pipeline operator in JavaScript, allowing developers to chain asynchronous request/response functions linearly. It serves a specific niche for users of the lightweight `polkadot` server who desire an Express.js-like middleware experience without significant overhead, focusing on readability and maintainability for simple API servers.","status":"active","version":"1.0.1","language":"javascript","source_language":"en","source_url":"https://github.com/TehShrike/polkadot-middleware","tags":["javascript","polkadot","http","middleware","server"],"install":[{"cmd":"npm install polkadot-middleware","lang":"bash","label":"npm"},{"cmd":"yarn add polkadot-middleware","lang":"bash","label":"yarn"},{"cmd":"pnpm add polkadot-middleware","lang":"bash","label":"pnpm"}],"dependencies":[{"reason":"This package is a middleware wrapper specifically designed for the `polkadot` HTTP server and cannot function independently.","package":"polkadot","optional":false}],"imports":[{"note":"The library primarily uses a default export pattern for both CJS and ESM.","wrong":"const { middleware } = require('polkadot-middleware')","symbol":"middleware","correct":"import middleware from 'polkadot-middleware'"},{"note":"`polkadot` itself is typically imported as a default export.","wrong":"const { polkadot } = require('polkadot')","symbol":"polkadot","correct":"import polkadot from 'polkadot'"}],"quickstart":{"code":"import polkadot from 'polkadot';\nimport middleware from 'polkadot-middleware';\n\nasync function handleErrors(next) {\n\treturn async (req, res) => {\n\t\ttry {\n\t\t\treturn await next(req, res);\n\t\t} catch (err) {\n\t\t\tres.statusCode = 500;\n\t\t\treturn err.message || err;\n\t\t}\n\t};\n}\n\nasync function setCacheControl(next) {\n\treturn async (req, res) => {\n\t\tres.setHeader(`Cache-Control`, `public, max-age=` + 3600);\n\t\treturn next(req, res);\n\t};\n}\n\nmiddleware(\n\tpolkadot,\n\thandleErrors,\n\tsetCacheControl,\n\t(req, res) => 'Sup dawg'\n).listen(8080, () => console.log('Server listening on http://localhost:8080'));","lang":"javascript","description":"Demonstrates chaining multiple middleware functions for error handling and cache control with a basic response using `polkadot-middleware`."},"warnings":[{"fix":"No immediate fix required, but be aware of future language changes that might make this library less critical.","message":"The primary utility of `polkadot-middleware` is as a temporary solution until the TC39 pipeline operator proposal is fully adopted and implemented in JavaScript runtimes. Once standardized, native language features may offer a more direct and potentially performant way to achieve similar composition.","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"Ensure you are using `polkadot` as your HTTP server. For other frameworks, use their native middleware solutions.","message":"This library is specifically designed for the `polkadot` HTTP server. It is not a general-purpose middleware solution and cannot be directly applied to other Node.js HTTP frameworks like Express.js, Koa, or Fastify.","severity":"gotcha","affected_versions":">=1.0.0"}],"env_vars":null,"last_verified":"2026-04-22T00:00:00.000Z","next_check":"2026-07-21T00:00:00.000Z","problems":[{"fix":"Run `npm install polkadot` or `yarn add polkadot`. Verify your `polkadot` import statement matches its export type (e.g., `import polkadot from 'polkadot'` for ESM).","cause":"The `polkadot` package was not installed or incorrectly imported, or an older version of `polkadot` with a different API is being used.","error":"TypeError: polkadot is not a function"},{"fix":"Run `npm install polkadot-middleware` or `yarn add polkadot-middleware`. Ensure the import statement is correct, typically `import middleware from 'polkadot-middleware'` or `const middleware = require('polkadot-middleware')`.","cause":"The `polkadot-middleware` package was not installed, incorrectly imported, or the import path is wrong.","error":"ReferenceError: middleware is not defined"}],"ecosystem":"npm","meta_description":null}