[breaking change] implement and default to useStrictShallowCopy, omitting getters

__performance_tests__/large-obj.js

@@ -0,0 +1,62 @@
+import {measure} from "./measure"
+import produce, {
+	setUseProxies,
+	setUseStrictShallowCopy,
+	enableAllPlugins
+} from "../dist/immer.cjs.production.min.js"
+
+enableAllPlugins()
+
+console.log("\n# large-obj - mutate large object\n")
+
+const MAX = 50
+
+const baseState = Object.fromEntries(
+	Array(10000)
+		.fill(0)
+		.map((_, i) => [i, i])
+)
+
+measure("immer (proxy) - with setUseStrictShallowCopy", () => {
+	setUseStrictShallowCopy(true)
+	setUseProxies(true)
+
+	for (let i = 0; i < MAX; i++) {
+		produce(baseState, draft => {
+			draft[5000]++
+		})
+	}
+})
+
+measure("immer (proxy) - without setUseStrictShallowCopy", () => {
+	setUseStrictShallowCopy(false)
+	setUseProxies(true)
+
+	for (let i = 0; i < MAX; i++) {
+		produce(baseState, draft => {
+			draft[5000]++
+		})
+	}
+})
+
+measure("immer (es5) - with setUseStrictShallowCopy", () => {
+	setUseStrictShallowCopy(true)
+	setUseProxies(false)
+
+	for (let i = 0; i < MAX; i++) {
+		produce(baseState, draft => {
+			draft[5000]++
+		})
+	}
+})
+
+measure("immer (es5) - without setUseStrictShallowCopy", () => {
+	setUseStrictShallowCopy(false)
+	setUseProxies(false)
+
+	for (let i = 0; i < MAX; i++) {
+		produce(baseState, draft => {
+			draft[5000]++
+		})
+	}
+})

__tests__/base.js

@@ -9,7 +9,6 @@ import {
 } from "../src/immer"
 import {each, shallowCopy, DRAFT_STATE} from "../src/internal"
 import deepFreeze from "deep-freeze"
-import cloneDeep from "lodash.clonedeep"
 import * as lodash from "lodash"
 
 jest.setTimeout(1000)
@@ -22,21 +21,39 @@ test("immer should have no dependencies", () => {
 	expect(require("../package.json").dependencies).toBeUndefined()
 })
 
-runBaseTest("proxy (no freeze)", true, false)
-runBaseTest("proxy (autofreeze)", true, true)
-runBaseTest("proxy (patch listener)", true, false, true)
-runBaseTest("proxy (autofreeze)(patch listener)", true, true, true)
-
-runBaseTest("es5 (no freeze)", false, false)
-runBaseTest("es5 (autofreeze)", false, true)
-runBaseTest("es5 (patch listener)", false, false, true)
-runBaseTest("es5 (autofreeze)(patch listener)", false, true, true)
+for (const useProxies of [true, false]) {
+	for (const autoFreeze of [true, false]) {
+		for (const useStrictShallowCopy of [true, false]) {
+			for (const useListener of [true, false]) {
+				const name = `${useProxies ? "proxy" : "es5"}:${
+					autoFreeze ? "auto-freeze=true" : "auto-freeze=false"
+				}:${
+					useStrictShallowCopy ? "shallow-copy=true" : "shallow-copy=false"
+				}:${useListener ? "use-listener=true" : "use-listener=false"}`
+				runBaseTest(
+					name,
+					useProxies,
+					autoFreeze,
+					useStrictShallowCopy,
+					useListener
+				)
+			}
+		}
+	}
+}
 
-function runBaseTest(name, useProxies, autoFreeze, useListener) {
+function runBaseTest(
+	name,
+	useProxies,
+	autoFreeze,
+	useStrictShallowCopy,
+	useListener
+) {
 	const listener = useListener ? function() {} : undefined
 	const {produce, produceWithPatches} = createPatchedImmer({
 		useProxies,
-		autoFreeze
+		autoFreeze,
+		useStrictShallowCopy
 	})
 
 	// When `useListener` is true, append a function to the arguments of every
@@ -904,10 +921,16 @@ function runBaseTest(name, useProxies, autoFreeze, useListener) {
 				expect(s[test]).toBeTruthy()
 				s.foo = true
 			})
-			expect(nextState).toEqual({
-				[test]: true,
-				foo: true
-			})
+			if (useStrictShallowCopy) {
+				expect(nextState).toEqual({
+					[test]: true,
+					foo: true
+				})
+			} else {
+				expect(nextState).toEqual({
+					foo: true
+				})
+			}
 		})
 
 		if (!global.USES_BUILD)
@@ -923,16 +946,26 @@ function runBaseTest(name, useProxies, autoFreeze, useListener) {
 					value: 1,
 					enumerable: false
 				})
+				// Non-enumerable primitive property that don't refer
+				Object.defineProperty(baseState, "baz", {
+					value: 1,
+					enumerable: false
+				})
+
+				// When using Proxy, even non-enumerable keys will be copied if it's changed.
+				const canReferNonEnumerableProperty = useProxies || useStrictShallowCopy
 				const nextState = produce(baseState, s => {
-					expect(s.foo).toBeTruthy()
-					expect(isEnumerable(s, "foo")).toBeFalsy()
-					s.bar++
-					expect(isEnumerable(s, "foo")).toBeFalsy()
-					s.foo.a++
-					expect(isEnumerable(s, "foo")).toBeFalsy()
-				})
-				expect(nextState.foo).toBeTruthy()
-				expect(isEnumerable(nextState, "foo")).toBeFalsy()
+					if (canReferNonEnumerableProperty) expect(s.foo).toBeTruthy()
+					if (useStrictShallowCopy) expect(isEnumerable(s, "foo")).toBeFalsy()
+					if (canReferNonEnumerableProperty) s.bar++
+					if (useStrictShallowCopy) expect(isEnumerable(s, "foo")).toBeFalsy()
+					if (canReferNonEnumerableProperty) s.foo.a++
+					if (useStrictShallowCopy) expect(isEnumerable(s, "foo")).toBeFalsy()
+				})
+				if (canReferNonEnumerableProperty) expect(nextState.foo).toBeTruthy()
+				if (useStrictShallowCopy)
+					expect(isEnumerable(nextState, "foo")).toBeFalsy()
+				if (useStrictShallowCopy) expect(nextState.baz).toBeTruthy()
 			})
 
 		it("can work with own computed props", () => {

__tests__/not-strict-copy.ts

@@ -0,0 +1,39 @@
+import produce, {enableAllPlugins, setUseStrictShallowCopy} from "../src/immer"
+
+enableAllPlugins()
+
+describe("setUseStrictShallowCopy(true)", () => {
+	test("keep descriptors", () => {
+		setUseStrictShallowCopy(true)
+
+		const base: Record<string, unknown> = {}
+		Object.defineProperty(base, "foo", {
+			value: "foo",
+			writable: false,
+			configurable: false
+		})
+		const copy = produce(base, (draft: any) => {
+			draft.bar = "bar"
+		})
+		expect(Object.getOwnPropertyDescriptor(copy, "foo")).toStrictEqual(
+			Object.getOwnPropertyDescriptor(base, "foo")
+		)
+	})
+})
+
+describe("setUseStrictShallowCopy(false)", () => {
+	test("ignore descriptors", () => {
+		setUseStrictShallowCopy(false)
+
+		const base: Record<string, unknown> = {}
+		Object.defineProperty(base, "foo", {
+			value: "foo",
+			writable: false,
+			configurable: false
+		})
+		const copy = produce(base, (draft: any) => {
+			draft.bar = "bar"
+		})
+		expect(Object.getOwnPropertyDescriptor(copy, "foo")).toBeUndefined()
+	})
+})

package.json

@@ -33,7 +33,7 @@
   "sideEffects": false,
   "scripts": {
     "test": "jest && yarn test:build && yarn test:flow",
-    "test:perf": "cd __performance_tests__ && babel-node add-data.js && babel-node todo.js && babel-node incremental.js",
+    "test:perf": "cd __performance_tests__ && babel-node add-data.js && babel-node todo.js && babel-node incremental.js && babel-node large-obj.js",
     "test:flow": "yarn flow check __tests__/flow",
     "test:build": "yarn build && NODE_ENV='production' yarn jest --config jest.config.build.js",
     "watch": "jest --watch",

src/core/current.ts

@@ -33,10 +33,14 @@ function currentImpl(value: any): any {
 			return state.base_
 		// Optimization: avoid generating new drafts during copying
 		state.finalized_ = true
-		copy = copyHelper(value, archType)
+		copy = copyHelper(
+			value,
+			archType,
+			state.scope_.immer_.useStrictShallowCopy_
+		)
 		state.finalized_ = false
 	} else {
-		copy = copyHelper(value, archType)
+		copy = copyHelper(value, archType, true)
 	}
 
 	each(copy, (key, childValue) => {
@@ -47,7 +51,7 @@ function currentImpl(value: any): any {
 	return archType === Archtype.Set ? new Set(copy) : copy
 }
 
-function copyHelper(value: any, archType: number): any {
+function copyHelper(value: any, archType: number, strict: boolean): any {
 	// creates a shallow copy, even if it is a map or set
 	switch (archType) {
 		case Archtype.Map:
@@ -56,5 +60,5 @@ function copyHelper(value: any, archType: number): any {
 			// Set will be cloned as array temporarily, so that we can replace individual items
 			return Array.from(value)
 	}
-	return shallowCopy(value)
+	return shallowCopy(value, strict)
 }

src/core/finalize.ts

@@ -83,7 +83,10 @@ function finalize(rootScope: ImmerScope, value: any, path?: PatchPath) {
 		const result =
 			// For ES5, create a good copy from the draft first, with added keys and without deleted keys.
 			state.type_ === ProxyType.ES5Object || state.type_ === ProxyType.ES5Array
-				? (state.copy_ = shallowCopy(state.draft_))
+				? (state.copy_ = shallowCopy(
+						state.draft_,
+						rootScope.immer_.useStrictShallowCopy_
+				  ))
 				: state.copy_
 		// Finalize all children of the copy
 		// For sets we clone before iterating, otherwise we can get in endless loop due to modifying during iteration, see #628

src/core/immerClass.ts

@@ -37,11 +37,19 @@ export class Immer implements ProducersFns {
 
 	autoFreeze_: boolean = true
 
-	constructor(config?: {useProxies?: boolean; autoFreeze?: boolean}) {
+	useStrictShallowCopy_: boolean = false
+
+	constructor(config?: {
+		useProxies?: boolean
+		autoFreeze?: boolean
+		useStrictShallowCopy?: boolean
+	}) {
 		if (typeof config?.useProxies === "boolean")
 			this.setUseProxies(config!.useProxies)
 		if (typeof config?.autoFreeze === "boolean")
 			this.setAutoFreeze(config!.autoFreeze)
+		if (typeof config?.useStrictShallowCopy === "boolean")
+			this.setUseStrictShallowCopy(config!.useStrictShallowCopy)
 	}
 
 	/**
@@ -195,6 +203,15 @@ export class Immer implements ProducersFns {
 		this.useProxies_ = value
 	}
 
+	/**
+	 * Pass true to enable strict shallow copy.
+	 *
+	 * By default, immer does not copy the object descriptors such as getter, setter and non-enumrable properties.
+	 */
+	setUseStrictShallowCopy(value: boolean) {
+		this.useStrictShallowCopy_ = value
+	}
+
 	applyPatches<T extends Objectish>(base: T, patches: Patch[]): T {
 		// If a patch replaces the entire state, take that replacement as base
 		// before applying patches

src/core/proxy.ts

@@ -17,6 +17,7 @@ import {
 	createProxy,
 	ProxyType
 } from "../internal"
+import {ImmerScope} from "./scope"
 
 interface ProxyBaseState extends ImmerBaseState {
 	assigned_: {
@@ -273,8 +274,15 @@ export function markChanged(state: ImmerState) {
 	}
 }
 
-export function prepareCopy(state: {base_: any; copy_: any}) {
+export function prepareCopy(state: {
+	base_: any
+	copy_: any
+	scope_: ImmerScope
+}) {
 	if (!state.copy_) {
-		state.copy_ = shallowCopy(state.base_)
+		state.copy_ = shallowCopy(
+			state.base_,
+			state.scope_.immer_.useStrictShallowCopy_
+		)
 	}
 }

src/immer.ts

@@ -67,6 +67,13 @@ export const setAutoFreeze = immer.setAutoFreeze.bind(immer)
  */
 export const setUseProxies = immer.setUseProxies.bind(immer)
 
+/**
+ * Pass true to enable strict shallow copy.
+ *
+ * By default, immer does not copy the object descriptors such as getter, setter and non-enumrable properties.
+ */
+export const setUseStrictShallowCopy = immer.setUseStrictShallowCopy.bind(immer)
+
 /**
  * Apply an array of Immer patches to the first argument.
  *

src/types/index.js.flow

@@ -84,6 +84,13 @@ declare export function setAutoFreeze(autoFreeze: boolean): void
  */
 declare export function setUseProxies(useProxies: boolean): void
 
+/**
+ * Pass false to disable strict shallow copy.
+ *
+ * By default, immer copies the object descriptors on creating new object.
+ */
+declare export function setUseStrictShallowCopy(useStrictShallowCopy: boolean): void
+
 declare export function applyPatches<S>(state: S, patches: Patch[]): S
 
 declare export function original<S>(value: S): S

src/utils/common.ts

@@ -162,8 +162,19 @@ export function latest(state: ImmerState): any {
 }
 
 /*#__PURE__*/
-export function shallowCopy(base: any) {
+export function shallowCopy(base: any, strict: boolean) {
 	if (Array.isArray(base)) return Array.prototype.slice.call(base)
+
+	if (!strict && isPlainObject(base)) {
+		const keys = Object.keys(base)
+		const obj: any = Object.create(Object.getPrototypeOf(base))
+		for (let i = 0; i < keys.length; i++) {
+			const key = keys[i]
+			obj[key] = base[key]
+		}
+		return obj
+	}
+
 	const descriptors = getOwnPropertyDescriptors(base)
 	delete descriptors[DRAFT_STATE as any]
 	let keys = ownKeys(descriptors)

website/docs/api.md

@@ -34,6 +34,7 @@ title: API overview
 | `produceWithPatches` | Works the same as `produce`, but instead of just returning the produced object, it returns a tuple, consisting of `[result, patches, inversePatches]`. | [Patches](./patches.mdx) |
 | `setAutoFreeze` | Enables / disables automatic freezing of the trees produces. By default enabled. | [Freezing](./freezing.mdx) |
 | `setUseProxies` | Can be used to disable or force the use of `Proxy` objects. Useful when filing bug reports. |  |
+| `setUseStrictShallowCopy` | Can be used to enable strict shallow copy. If enable, immer copies non-enumerable properties as much as possible. | [Classes](./complex-objects.md) |
 
 ## Importing immer