Allow explicitly unsetting hooks on .extend()

readme.md

@@ -487,6 +487,8 @@ You can pass headers as a `Headers` instance or a plain object.
 You can remove a header with `.extend()` by passing the header with an `undefined` value.
 Passing `undefined` as a string removes the header only if it comes from a `Headers` instance.
 
+Similarly, you can remove existing `hooks` entries by extending the hook with an explicit `undefined`.
+
 ```js
 import ky from 'ky';
 
@@ -496,16 +498,26 @@ const original = ky.create({
 	headers: {
 		rainbow: 'rainbow',
 		unicorn: 'unicorn'
-	}
+	},
+	hooks: {
+		beforeRequest: [ () => console.log('before 1') ],
+		afterResponse: [ () => console.log('after 1') ],
+	},
 });
 
 const extended = original.extend({
 	headers: {
 		rainbow: undefined
+	},
+	hooks: {
+		beforeRequest: undefined,
+		afterResponse: [ () => console.log('after 2') ],
 	}
 });
 
 const response = await extended(url).json();
+//=> after 1
+//=> after 2
 
 console.log('rainbow' in response);
 //=> false

source/core/Ky.ts

@@ -1,6 +1,5 @@
 import {HTTPError} from '../errors/HTTPError.js';
 import {TimeoutError} from '../errors/TimeoutError.js';
-import type {Hooks} from '../types/hooks.js';
 import type {
 	Input,
 	InternalOptions,
@@ -9,7 +8,7 @@ import type {
 	SearchParamsInit,
 } from '../types/options.js';
 import {type ResponsePromise} from '../types/ResponsePromise.js';
-import {deepMerge, mergeHeaders} from '../utils/merge.js';
+import {mergeHeaders, mergeHooks} from '../utils/merge.js';
 import {normalizeRequestMethod, normalizeRetryOptions} from '../utils/normalize.js';
 import timeout, {type TimeoutOptions} from '../utils/timeout.js';
 import delay from '../utils/delay.js';
@@ -133,7 +132,7 @@ export class Ky {
 			...(credentials && {credentials}), // For exactOptionalPropertyTypes
 			...options,
 			headers: mergeHeaders((this._input as Request).headers, options.headers),
-			hooks: deepMerge<Required<Hooks>>(
+			hooks: mergeHooks(
 				{
 					beforeRequest: [],
 					beforeRetry: [],

source/utils/merge.ts

@@ -1,4 +1,5 @@
 import type {KyHeadersInit, Options} from '../types/options.js';
+import type {Hooks} from '../types/hooks.js';
 import {isObject} from './is.js';
 
 export const validateAndMerge = (...sources: Array<Partial<Options> | undefined>): Partial<Options> => {
@@ -27,10 +28,26 @@ export const mergeHeaders = (source1: KyHeadersInit = {}, source2: KyHeadersInit
 	return result;
 };
 
+function newHookValue<K extends keyof Hooks>(original: Hooks, incoming: Hooks, property: K): Required<Hooks>[K] {
+	return (Object.hasOwn(incoming, property) && incoming[property] === undefined)
+		? []
+		: deepMerge<Required<Hooks>[K]>(original[property] ?? [], incoming[property] ?? []);
+}
+
+export const mergeHooks = (original: Hooks = {}, incoming: Hooks = {}): Required<Hooks> => (
+	{
+		beforeRequest: newHookValue(original, incoming, 'beforeRequest'),
+		beforeRetry: newHookValue(original, incoming, 'beforeRetry'),
+		afterResponse: newHookValue(original, incoming, 'afterResponse'),
+		beforeError: newHookValue(original, incoming, 'beforeError'),
+	}
+);
+
 // TODO: Make this strongly-typed (no `any`).
 export const deepMerge = <T>(...sources: Array<Partial<T> | undefined>): T => {
 	let returnValue: any = {};
 	let headers = {};
+	let hooks = {};
 
 	for (const source of sources) {
 		if (Array.isArray(source)) {
@@ -48,6 +65,11 @@ export const deepMerge = <T>(...sources: Array<Partial<T> | undefined>): T => {
 				returnValue = {...returnValue, [key]: value};
 			}
 
+			if (isObject((source as any).hooks)) {
+				hooks = mergeHooks(hooks, (source as any).hooks);
+				returnValue.hooks = hooks;
+			}
+
 			if (isObject((source as any).headers)) {
 				headers = mergeHeaders(headers, (source as any).headers);
 				returnValue.headers = headers;

test/main.ts

@@ -500,6 +500,7 @@ test('ky.create() with deep array', async t => {
 
 	let isOriginBeforeRequestTrigged = false;
 	let isExtendBeforeRequestTrigged = false;
+	let isExtendAfterResponseTrigged = false;
 
 	const extended = ky.create({
 		hooks: {
@@ -518,11 +519,17 @@ test('ky.create() with deep array', async t => {
 					isExtendBeforeRequestTrigged = true;
 				},
 			],
+			afterResponse: [
+				() => {
+					isExtendAfterResponseTrigged = true;
+				},
+			],
 		},
 	});
 
 	t.is(isOriginBeforeRequestTrigged, true);
 	t.is(isExtendBeforeRequestTrigged, true);
+	t.is(isExtendAfterResponseTrigged, true);
 
 	const {ok} = await extended.head(server.url);
 	t.true(ok);
@@ -549,6 +556,7 @@ const extendHooksMacro = test.macro<[{useFunction: boolean}]>(async (t, {useFunc
 	});
 
 	let isOriginBeforeRequestTrigged = false;
+	let isOriginAfterResponseTrigged = false;
 	let isExtendBeforeRequestTrigged = false;
 
 	const intermediateOptions = {
@@ -558,6 +566,11 @@ const extendHooksMacro = test.macro<[{useFunction: boolean}]>(async (t, {useFunc
 					isOriginBeforeRequestTrigged = true;
 				},
 			],
+			afterResponse: [
+				() => {
+					isOriginAfterResponseTrigged = true;
+				},
+			],
 		},
 	};
 	const extendedOptions = {
@@ -577,6 +590,7 @@ const extendHooksMacro = test.macro<[{useFunction: boolean}]>(async (t, {useFunc
 	await extended(server.url);
 
 	t.is(isOriginBeforeRequestTrigged, true);
+	t.is(isOriginAfterResponseTrigged, true);
 	t.is(isExtendBeforeRequestTrigged, true);
 
 	const {ok} = await extended.head(server.url);
@@ -639,6 +653,48 @@ test('ky.extend() with function retains parent defaults when not specified', asy
 	await server.close();
 });
 
+test('ky.extend() can remove hooks', async t => {
+	const server = await createHttpTestServer();
+	server.get('/', (_request, response) => {
+		response.end();
+	});
+
+	let isOriginalBeforeRequestTrigged = false;
+	let isOriginalAfterResponseTrigged = false;
+
+	const extended = ky
+		.extend({
+			hooks: {
+				beforeRequest: [
+					() => {
+						isOriginalBeforeRequestTrigged = true;
+					},
+				],
+				afterResponse: [
+					() => {
+						isOriginalAfterResponseTrigged = true;
+					},
+				],
+			},
+		})
+		.extend({
+			hooks: {
+				beforeRequest: undefined,
+				afterResponse: [],
+			},
+		});
+
+	await extended(server.url);
+
+	t.is(isOriginalBeforeRequestTrigged, false);
+	t.is(isOriginalAfterResponseTrigged, true);
+
+	const {ok} = await extended.head(server.url);
+	t.true(ok);
+
+	await server.close();
+});
+
 test('throws DOMException/Error with name AbortError when aborted by user', async t => {
 	const server = await createHttpTestServer();
 	// eslint-disable-next-line @typescript-eslint/no-empty-function