safeWriteHead() — fastify Function Reference

Architecture documentation for the safeWriteHead() function in reply.js from the fastify codebase.

Function javascript CoreKernel LifecycleManager called by 1

Entity Profile

CoreKernel→ LifecycleManager→ safeWriteHead() — fastify Function Reference

Dependency Diagram

graph TD
  e0d1c987_ac40_1669_63e9_2bab4d6f95ff["safeWriteHead()"]
  4bcd71dc_1ec2_5fe8_b8ff_4a371e392925["reply.js"]
  e0d1c987_ac40_1669_63e9_2bab4d6f95ff -->|defined in| 4bcd71dc_1ec2_5fe8_b8ff_4a371e392925
  8460cb7c_51e5_baba_0f16_9ea8d190d139["onSendEnd()"]
  8460cb7c_51e5_baba_0f16_9ea8d190d139 -->|calls| e0d1c987_ac40_1669_63e9_2bab4d6f95ff
  style e0d1c987_ac40_1669_63e9_2bab4d6f95ff fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

lib/reply.js lines 551–561

function safeWriteHead (reply, statusCode) {
  const res = reply.raw
  try {
    res.writeHead(statusCode, reply[kReplyHeaders])
  } catch (err) {
    if (err.code === 'ERR_HTTP_HEADERS_SENT') {
      reply.log.warn(`Reply was already sent, did you forget to "return reply" in the "${reply.request.raw.url}" (${reply.request.raw.method}) route?`)
    }
    throw err
  }
}