koa-compose

library4.1.0jsnpmunverified

Utility to compose Koa middleware functions into a single middleware. Current stable version is 4.1.0. Low release cadence; maintained as part of the Koa ecosystem. Key differentiator: it is the canonical middleware composition function for Koa, supporting async/await and error handling through promises. Alternatives like `koa-convert` or custom loops exist, but this is minimal and standard.

web-framework

npm install koa-compose

github ↗package ↗

INSTALL

IMPORT

SIG · KOA-COMPOSE

koa-compose

web-frameworkjavascriptv4.1.0

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

compose

✓ import compose from 'koa-compose'

✗ const compose = require('koa-compose')

ESM default import is correct in Node >=12 with ESM enabled; require works in CommonJS but is less common for modern Koa projects.

compose

✓ const compose = require('koa-compose')

✗ const { compose } = require('koa-compose')

CommonJS import works but must be default, not destructured.

compose

✓ import compose from 'koa-compose'

✗ import { compose } from 'koa-compose'

Named import is incorrect; koa-compose exports a function as default.

Demonstrates composing two Koa middleware functions (logger and responseTime) using compose, then applying to a Koa app.

import Koa from 'koa'; import compose from 'koa-compose'; const app = new Koa(); const logger = async (ctx, next) => { console.log(`${ctx.method} ${ctx.url}`); await next(); }; const responseTime = async (ctx, next) => { const start = Date.now(); await next(); const ms = Date.now() - start; ctx.set('X-Response-Time', `${ms}ms`); }; const composed = compose([logger, responseTime]); app.use(composed); app.listen(3000); console.log('Server running on port 3000');

Debug

Known issues

gotchacompose expects an array of middleware; passing non-array will throw.

fix

Always wrap middleware in an array: compose([mw1, mw2])

affects: >=4.0.0

gotchaMiddleware must be async functions returning Promises; otherwise compose may not work correctly.

fix

Define middleware as async (ctx, next) => { await next(); }

affects: >=4.0.0

gotchacompose returns a single middleware function; cannot be used directly as router-level middleware without wrapping.

fix

Use the returned function with app.use() or router middleware stack.

affects: >=4.0.0

Errors

Common errors & fixes

TypeError: middleware is not a function

Passing non-array or undefined to compose.

fix

Ensure compose is called with an array: compose([func1, func2])

Error: next() called multiple times

Calling next() more than once in a middleware function.

fix

Ensure each middleware calls next() exactly once, or handle conditional logic properly.

ReferenceError: compose is not defined

Missing import or using incorrect import syntax.

fix

Use proper import: import compose from 'koa-compose' or const compose = require('koa-compose')

Upgrade

Version history

4.1.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

4 hits · last 30 days

node

Resources

githubhttps://github.com/koajs/compose ↗

packagehttps://www.npmjs.com/package/koa-compose ↗