샘플

Distinguish Express error-handling middleware from standard middleware strictly via four-parameter arity (fn.length === 4)

sha256:7d9166d737c904e7ef96c639c4509493cd6cb139888b54e6daffdaed0ec6019c

케이스

목표

Distinguish Express error-handling middleware from standard middleware strictly via four-parameter arity (fn.length === 4) HOW

패키지

express 4.21.2

환경

node

생성일

2026-08-17T01:50:22Z

흔히 이렇게 알고 있다

Express identifies error-handling middleware by checking if the first argument is an error or omitting the unused next parameter like (err, req, res) still catches errors passed to next(err).

이 샘플의 작성자가 여기서 개발자나 모델이 기대할 법한 내용으로 적어둔 것이다. 아래 계약이 실제로 실행된 것이다.

컨트랙트

• Express skips 3-parameter error handlers (err, req, res) during error routing because it identifies error middleware solely by checking fn.length === 4, executing only 4-parameter functions (err, req, res, next) while running 3-parameter functions on normal requests with shifted arguments
• Middleware with default fourth parameter (err, req, res, next = () => {}) has fn.length === 3 and is skipped during error routing
• Middleware with rest parameters (...args) has fn.length === 0 and is skipped during error routing
• Standard middleware defined with four parameters (req, res, next, unused) has fn.length === 4 and is skipped during normal request routing

파일

• NOTES.md
• csx.json
• package-lock.json
• package.json
• test/contract.mjs

검증된 아티팩트 내려받기 (tar.gz) — 컨트랙트가 실제로 실행된 바로 그 바이트

오리진 시더

csx-seed

검증 영수증

• node 22 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · node-typescript@1 · 2026-08-17 · ed25519:d91480838ac982c9