Function executeMiddleware

packages/start-server-core/src/createStartHandler.ts:256–302

* Execute a middleware chain

(middlewares: Array<TODO>, ctx: TODO)

 * Execute a middleware chain
 */
function executeMiddleware(middlewares: Array<TODO>, ctx: TODO): Promise<TODO> {
  let index = -1

  const next = async (nextCtx?: TODO): Promise<TODO> => {
    // Merge context if provided using safeObjectMerge for prototype pollution prevention
    if (nextCtx) {
      if (nextCtx.context) {
        ctx.context = safeObjectMerge(ctx.context, nextCtx.context)
      }
      // Copy own properties except context (Object.keys returns only own enumerable properties)
      for (const key of Object.keys(nextCtx)) {
        if (key !== 'context') {
          ctx[key] = nextCtx[key]
        }
      }
    }

    index++
    const middleware = middlewares[index]
    if (!middleware) return ctx

    let result: TODO
    try {
      result = await middleware({ ...ctx, next })
    } catch (err) {
      if (isSpecialResponse(err)) {
        ctx.response = err
        return ctx
      }
      throw err
    }

    const normalized = handleCtxResult(result)
    if (normalized) {
      if (normalized.response !== undefined) {
        ctx.response = normalized.response
      }
      if (normalized.context) {
        ctx.context = safeObjectMerge(ctx.context, normalized.context)
      }
    }

    return ctx
  }

  return next()
}

/**
 * Wrap a route handler as middleware