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InterceptorHandler<T>

The shape of an interceptor handler registered with interceptors.request.use() or interceptors.response.use().

Types​

interface InterceptorHandler<T> {
  fulfilled?: (value: T) => T | Promise<T>
  rejected?: (err: unknown) => unknown
}

interface InterceptorManager<T> {
  use(handler: InterceptorHandler<T>): number
  use(
    onFulfilled?: (value: T) => T | Promise<T>,
    onRejected?: (err: unknown) => unknown,
  ): number
  eject(id: number): void
}

InterceptorHandler fields​

FieldTypeDescription
fulfilled(value: T) => T | Promise<T>Called on the success path. For request interceptors, T is RequestConfig. For response interceptors, T is HttpResponse<unknown>.
rejected(err: unknown) => unknownCalled on the error path. Throw to propagate the error, or return a value to recover.

InterceptorManager methods​

MethodDescription
use(handler)Register an interceptor. Returns an ID for later removal.
use(onFulfilled?, onRejected?)Register with separate callbacks (axios-compatible overload).
eject(id)Remove a previously registered interceptor by ID.

Example​

import { createClient } from '@parcely/core'

const http = createClient({ baseURL: 'https://api.example.com' })

// Object form
const id = http.interceptors.request.use({
  fulfilled: (config) => ({
    ...config,
    headers: { ...config.headers, 'X-Trace': crypto.randomUUID() },
  }),
  rejected: (err) => { throw err },
})

// Callback form (axios-compatible)
http.interceptors.response.use(
  (response) => response,
  (err) => { console.error(err); throw err },
)

// Remove an interceptor
http.interceptors.request.eject(id)

Execution order​

  1. Request interceptors run in registration order.
  2. The HTTP request is made.
  3. Response interceptors run in registration order.
  4. If any interceptor throws, subsequent interceptors on the success path are skipped, but error-path handlers run.

See also​