HookResult

Every action in this package resolves to a HookResult. Actions never throw.

type HookResult<T> =
  | ({ success: true } & T)
  | { success: false; error: string; code: string | null; cause: unknown };

import type { HookResult } from '@timonwa/firebase-hooks';

On success

success: true plus whatever that action returns. Sign-ins add user and credential, where credential is Firebase's raw UserCredential — nothing is withheld or reshaped.

const result = await login(email, password);
if (result.success) {
  result.user; // User
  result.credential; // UserCredential
}

Actions with nothing to return resolve to plain { success: true }.

On failure

code and cause are always Firebase's own. Only error is ever processed, and only if you opt in — see Error handling.

Narrowing

success is a discriminant, so TypeScript narrows on it:

const result = await login(email, password);
if (!result.success) {
  result.code; // string | null
  return;
}
result.user; // User — narrowed, no optional chaining needed

Related types

HookErrorOptions — the formatErrorMessage option every hook accepts.

HookErrorContext — what the provider's onError observer receives: { action, code, message }.