Dev Server and HMR | blade47/next.js Wiki | doc0

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Dev Server and HMR | blade47/next.js Wiki | doc0

child = fork(startServerPath, {
  stdio: 'inherit',
  execArgv,
  env: {
    ...defaultEnv,
    ...(isTurbopack ? { TURBOPACK: process.env.TURBOPACK } : undefined),
    __NEXT_DEV_SERVER: '1',
    NEXT_PRIVATE_WORKER: '1',
    NEXT_PRIVATE_TRACE_ID: traceId,
    NODE_OPTIONS: formattedNodeOptions,
  },
})

Method / Property	Return Type	Purpose in DevServer
`ensurePage(opts)`	`Promise<void>`	Triggers compilation of a page entry on-demand if not already built.
`getCompilationError(page)`	`Promise<any>`	Retrieves compilation errors for a given page route from the bundler.
`appIsrManifest`	`Record<string, boolean>`	Exposes the Incremental Static Regeneration manifest state for cached routes.
`sendHmrMessage(msg)`	`void`	Broadcasts an HMR message to all active browser client sockets.

function sendEnqueuedMessages() {
  for (const [, issueMap] of currentEntryIssues) {
    if (
      [...issueMap.values()].filter((i) => i.severity !== 'warning').length >
      0
    ) {
      // During compilation errors we want to delay the HMR events until errors are fixed
      return
    }
  }
  // Broadcast enqueued messages to connected clients...
}

async function calculateFileHash(
  filePath: string,
  algorithm: string = 'sha256'
): Promise<string | undefined> {
  if (
    !(await fs.access(filePath).then(
      () => true,
      () => false
    ))
  ) {
    return
  }
  const fileBuffer = await fs.readFile(filePath)
  const hash = createHash(algorithm)
  hash.update(fileBuffer)
  return hash.digest('hex')
}

// Attempt to update code on the fly, fall back to a hard reload.
function tryApplyUpdatesWebpack(sendMessage: (message: string) => void) {
  if (!isUpdateAvailable() || !canApplyUpdates()) {
    resolvePendingHotUpdateWebpack()
    dispatcher.onBuildOk()
    reportHmrLatency(sendMessage, [], webpackStartMsSinceEpoch!, Date.now())
    return
  }
  // Applies module hot updates via module.hot.check()
}