use native structuredClone on node, cloudflare workers, and in tests (#3166)

Currently, we only use native `structuredClone` in the browser, falling
back to `JSON.parse(JSON.stringify(...))` elsewhere, despite Node
supporting `structuredClone` [since
v17](https://developer.mozilla.org/en-US/docs/Web/API/structuredClone)
and Cloudflare Workers supporting it [since
2022](https://blog.cloudflare.com/standards-compliant-workers-api/).
This PR adjusts our shim to use the native `structuredClone` on all
platforms, if available.

Additionally, `jsdom` doesn't implement `structuredClone`, a bug [open
since 2022](https://github.com/jsdom/jsdom/issues/3363). This PR patches
`jsdom` environment in all packages/apps that use it for tests.

Also includes a driveby removal of `deepCopy`, a function that is
strictly inferior to `structuredClone`.

### Change Type

<!-- ❗ Please select a 'Scope' label ❗️ -->

- [x] `sdk` — Changes the tldraw SDK
- [x] `dotcom` — Changes the tldraw.com web app
- [ ] `docs` — Changes to the documentation, examples, or templates.
- [ ] `vs code` — Changes to the vscode plugin
- [ ] `internal` — Does not affect user-facing stuff

<!-- ❗ Please select a 'Type' label ❗️ -->

- [ ] `bugfix` — Bug fix
- [ ] `feature` — New feature
- [x] `improvement` — Improving existing features
- [x] `chore` — Updating dependencies, other boring stuff
- [ ] `galaxy brain` — Architectural changes
- [ ] `tests` — Changes to any test code
- [ ] `tools` — Changes to infrastructure, CI, internal scripts,
debugging tools, etc.
- [ ] `dunno` — I don't know


### Test Plan

1. A smoke test would be enough

- [ ] Unit Tests
- [x] End to end tests

.eslintignore

@@ -28,4 +28,6 @@ apps/vscode/extension/editor/tldraw-assets.json
 **/scripts/upload-sourcemaps.js
 **/coverage/**/*
 
-apps/dotcom/public/sw.js
+apps/dotcom/public/sw.js
+
+patchedJestJsDom.js

.eslintrc.js

@@ -66,6 +66,10 @@ module.exports = {
 				message: 'Use the getFromSessionStorage/setInSessionStorage helpers instead',
 			},
 		],
+		'no-restricted-globals': [
+			'error',
+			{ name: 'structuredClone', message: 'Use structuredClone from @tldraw/util instead' },
+		],
 	},
 	parser: '@typescript-eslint/parser',
 	parserOptions: {

.github/workflows/checks.yml

@@ -38,15 +38,15 @@ jobs:
       - name: Check for installation warnings
         run: 'yarn | grep -vzq "with warnings"'
 
+      - name: Check tsconfigs
+        run: yarn check-tsconfigs
+
       - name: Typecheck
         run: yarn build-types
 
       - name: Check scripts
         run: yarn check-scripts
 
-      - name: Check tsconfigs
-        run: yarn check-tsconfigs
-
       - name: Check PR template
         run: yarn update-pr-template --check
 

apps/docs/app/api/ai/route.ts

@@ -1,6 +1,7 @@
 import { SearchResult } from '@/types/search-types'
 import { getDb } from '@/utils/ContentDatabase'
 import { SEARCH_RESULTS, searchBucket, sectionTypeBucket } from '@/utils/search-api'
+import { structuredClone } from '@tldraw/utils'
 import assert from 'assert'
 import { NextRequest } from 'next/server'
 

apps/docs/app/api/search/route.ts

@@ -1,6 +1,7 @@
 import { SearchResult } from '@/types/search-types'
 import { getDb } from '@/utils/ContentDatabase'
 import { SEARCH_RESULTS, searchBucket, sectionTypeBucket } from '@/utils/search-api'
+import { structuredClone } from '@tldraw/utils'
 import { NextRequest } from 'next/server'
 
 type Data = {

apps/docs/package.json

@@ -49,6 +49,7 @@
 		"@microsoft/tsdoc": "^0.14.2",
 		"@radix-ui/react-accordion": "^1.1.2",
 		"@radix-ui/react-navigation-menu": "^1.1.4",
+		"@tldraw/utils": "workspace:*",
 		"@types/broken-link-checker": "^0.7.1",
 		"@types/node": "~20.11",
 		"@types/sqlite3": "^3.1.9",

apps/docs/tsconfig.json

@@ -24,5 +24,10 @@
 		".next/types/**/*.ts",
 		"watcher.ts"
 	],
-	"exclude": ["node_modules", ".next"]
+	"exclude": ["node_modules", ".next"],
+	"references": [
+		{
+			"path": "../../packages/utils"
+		}
+	]
 }

apps/dotcom/package.json

@@ -58,7 +58,7 @@
 		"roots": [
 			"<rootDir>"
 		],
-		"testEnvironment": "jsdom",
+		"testEnvironment": "../../../packages/utils/patchedJestJsDom.js",
 		"transformIgnorePatterns": [
 			"node_modules/(?!(nanoid|nanoevents)/)"
 		],

apps/examples/src/examples/speech-bubble/SpeechBubble/SpeechBubbleUtil.tsx

@@ -15,7 +15,6 @@ import {
 	Vec,
 	VecModel,
 	ZERO_INDEX_KEY,
-	deepCopy,
 	getDefaultColorTheme,
 	resizeBox,
 	structuredClone,
@@ -143,7 +142,7 @@ export class SpeechBubbleUtil extends ShapeUtil<SpeechBubbleShape> {
 			}
 		}
 
-		const next = deepCopy(shape)
+		const next = structuredClone(shape)
 		next.props.tail.x = newPoint.x / w
 		next.props.tail.y = newPoint.y / h
 

packages/editor/package.json

@@ -84,7 +84,7 @@
 	},
 	"jest": {
 		"preset": "config/jest/node",
-		"testEnvironment": "jsdom",
+		"testEnvironment": "../../../packages/utils/patchedJestJsDom.js",
 		"fakeTimers": {
 			"enableGlobally": true
 		},

packages/editor/src/lib/editor/Editor.ts

@@ -47,7 +47,6 @@ import {
 	assert,
 	compact,
 	dedupe,
-	deepCopy,
 	getIndexAbove,
 	getIndexBetween,
 	getIndices,
@@ -5224,7 +5223,7 @@ export class Editor extends EventEmitter<TLEventMap> {
 					? getIndexBetween(shape.index, siblingAbove.index)
 					: getIndexAbove(shape.index)
 
-				let newShape: TLShape = deepCopy(shape)
+				let newShape: TLShape = structuredClone(shape)
 
 				if (
 					this.isShapeOfType<TLArrowShape>(shape, 'arrow') &&
@@ -7867,13 +7866,13 @@ export class Editor extends EventEmitter<TLEventMap> {
 			let newShape: TLShape
 
 			if (preserveIds) {
-				newShape = deepCopy(shape)
+				newShape = structuredClone(shape)
 				idMap.set(shape.id, shape.id)
 			} else {
 				const id = idMap.get(shape.id)!
 
 				// Create the new shape (new except for the id)
-				newShape = deepCopy({ ...shape, id })
+				newShape = structuredClone({ ...shape, id })
 			}
 
 			if (rootShapeIds.includes(shape.id)) {

packages/namespaced-tldraw/package.json

@@ -57,7 +57,7 @@
 	},
 	"jest": {
 		"preset": "config/jest/node",
-		"testEnvironment": "jsdom",
+		"testEnvironment": "../../../packages/utils/patchedJestJsDom.js",
 		"fakeTimers": {
 			"enableGlobally": true
 		},

packages/store/src/lib/devFreeze.ts

@@ -1,3 +1,5 @@
+import { STRUCTURED_CLONE_OBJECT_PROTOTYPE } from '@tldraw/utils'
+
 /**
  * Freeze an object when in development mode. Copied from
  * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze
@@ -17,7 +19,15 @@ export function devFreeze<T>(object: T): T {
 		return object
 	}
 	const proto = Object.getPrototypeOf(object)
-	if (proto && !(proto === Array.prototype || proto === Object.prototype)) {
+	if (
+		proto &&
+		!(
+			Array.isArray(object) ||
+			proto === Object.prototype ||
+			proto === null ||
+			proto === STRUCTURED_CLONE_OBJECT_PROTOTYPE
+		)
+	) {
 		console.error('cannot include non-js data in a record', object)
 		throw new Error('cannot include non-js data in a record')
 	}

packages/tldraw/package.json

@@ -78,7 +78,7 @@
 	},
 	"jest": {
 		"preset": "config/jest/node",
-		"testEnvironment": "jsdom",
+		"testEnvironment": "../../../packages/utils/patchedJestJsDom.js",
 		"fakeTimers": {
 			"enableGlobally": true
 		},

packages/tldraw/src/lib/shapes/arrow/ArrowShapeUtil.tsx

@@ -27,11 +27,11 @@ import {
 	Vec,
 	arrowShapeMigrations,
 	arrowShapeProps,
-	deepCopy,
 	getArrowTerminalsInArrowSpace,
 	getDefaultColorTheme,
 	mapObjectMapValues,
 	objectMapEntries,
+	structuredClone,
 	toDomPrecision,
 	useIsEditing,
 } from '@tldraw/editor'
@@ -194,7 +194,7 @@ export class ArrowShapeUtil extends ShapeUtil<TLArrowShape> {
 
 		// Start or end, pointing the arrow...
 
-		const next = deepCopy(shape) as TLArrowShape
+		const next = structuredClone(shape) as TLArrowShape
 
 		if (this.editor.inputs.ctrlKey) {
 			// todo: maybe double check that this isn't equal to the other handle too?
@@ -420,7 +420,7 @@ export class ArrowShapeUtil extends ShapeUtil<TLArrowShape> {
 
 		const terminals = getArrowTerminalsInArrowSpace(this.editor, shape)
 
-		const { start, end } = deepCopy<TLArrowShape['props']>(shape.props)
+		const { start, end } = structuredClone<TLArrowShape['props']>(shape.props)
 		let { bend } = shape.props
 
 		// Rescale start handle if it's not bound to a shape

packages/tldraw/src/lib/shapes/image/ImageShapeUtil.tsx

@@ -7,9 +7,9 @@ import {
 	TLOnDoubleClickHandler,
 	TLShapePartial,
 	Vec,
-	deepCopy,
 	imageShapeMigrations,
 	imageShapeProps,
+	structuredClone,
 	toDomPrecision,
 } from '@tldraw/editor'
 import { useEffect, useState } from 'react'
@@ -254,7 +254,7 @@ export class ImageShapeUtil extends BaseBoxShapeUtil<TLImageShape> {
 			return
 		}
 
-		const crop = deepCopy(props.crop) || {
+		const crop = structuredClone(props.crop) || {
 			topLeft: { x: 0, y: 0 },
 			bottomRight: { x: 1, y: 1 },
 		}

packages/tldraw/src/lib/shapes/line/LineShapeUtil.test.tsx

@@ -3,8 +3,8 @@ import {
 	TLGeoShape,
 	TLLineShape,
 	createShapeId,
-	deepCopy,
 	sortByIndex,
+	structuredClone,
 } from '@tldraw/editor'
 import { TestEditor } from '../../../test/TestEditor'
 import { TL } from '../../../test/test-jsx'
@@ -278,7 +278,7 @@ describe('Misc', () => {
 	it('preserves handle positions on spline type change', () => {
 		editor.select(id)
 		const shape = getShape()
-		const prevPoints = deepCopy(shape.props.points)
+		const prevPoints = structuredClone(shape.props.points)
 
 		editor.updateShapes([
 			{

packages/tldraw/src/lib/tools/SelectTool/childStates/Crop/children/crop_helpers.ts

@@ -4,7 +4,7 @@ import {
 	TLImageShapeCrop,
 	TLShapePartial,
 	Vec,
-	deepCopy,
+	structuredClone,
 } from '@tldraw/editor'
 
 export type ShapeWithCrop = TLBaseShape<string, { w: number; h: number; crop: TLImageShapeCrop }>
@@ -44,7 +44,7 @@ export function getTranslateCroppedImageChange(
 
 	const yCrop = oldCrop.bottomRight.y - oldCrop.topLeft.y
 	const xCrop = oldCrop.bottomRight.x - oldCrop.topLeft.x
-	const newCrop = deepCopy(oldCrop)
+	const newCrop = structuredClone(oldCrop)
 
 	newCrop.topLeft.x = Math.min(1 - xCrop, Math.max(0, newCrop.topLeft.x - delta.x / w))
 	newCrop.topLeft.y = Math.min(1 - yCrop, Math.max(0, newCrop.topLeft.y - delta.y / h))

packages/tldraw/src/lib/tools/SelectTool/childStates/Cropping.ts

@@ -9,7 +9,7 @@ import {
 	TLPointerEventInfo,
 	TLShapePartial,
 	Vec,
-	deepCopy,
+	structuredClone,
 } from '@tldraw/editor'
 import { MIN_CROP_SIZE } from './Crop/crop-constants'
 import { CursorTypeMap } from './PointingResizeHandle'
@@ -101,7 +101,7 @@ export class Cropping extends StateNode {
 		const change = currentPagePoint.clone().sub(originPagePoint).rot(-shape.rotation)
 
 		const crop = props.crop ?? this.getDefaultCrop()
-		const newCrop = deepCopy(crop)
+		const newCrop = structuredClone(crop)
 
 		const newPoint = new Vec(shape.x, shape.y)
 		const pointDelta = new Vec(0, 0)

packages/tlschema/src/shapes/TLLineShape.ts

@@ -1,5 +1,11 @@
 import { defineMigrations } from '@tldraw/store'
-import { IndexKey, deepCopy, getIndices, objectMapFromEntries, sortByIndex } from '@tldraw/utils'
+import {
+	IndexKey,
+	getIndices,
+	objectMapFromEntries,
+	sortByIndex,
+	structuredClone,
+} from '@tldraw/utils'
 import { T } from '@tldraw/validate'
 import { StyleProp } from '../styles/StyleProp'
 import { DefaultColorStyle } from '../styles/TLColorStyle'
@@ -52,14 +58,14 @@ export const lineShapeMigrations = defineMigrations({
 	migrators: {
 		[lineShapeVersions.AddSnapHandles]: {
 			up: (record: any) => {
-				const handles = deepCopy(record.props.handles as Record<string, any>)
+				const handles = structuredClone(record.props.handles as Record<string, any>)
 				for (const id in handles) {
 					handles[id].canSnap = true
 				}
 				return { ...record, props: { ...record.props, handles } }
 			},
 			down: (record: any) => {
-				const handles = deepCopy(record.props.handles as Record<string, any>)
+				const handles = structuredClone(record.props.handles as Record<string, any>)
 				for (const id in handles) {
 					delete handles[id].canSnap
 				}

packages/tlsync/package.json

@@ -44,7 +44,7 @@
 	},
 	"jest": {
 		"preset": "config/jest/node",
-		"testEnvironment": "jsdom",
+		"testEnvironment": "../../../packages/utils/patchedJestJsDom.js",
 		"moduleNameMapper": {
 			"^~(.*)": "<rootDir>/src/$1"
 		},

packages/tlsync/src/lib/TLSyncRoom.ts

@@ -13,10 +13,12 @@ import { DocumentRecordType, PageRecordType, TLDOCUMENT_ID } from '@tldraw/tlsch
 import {
 	IndexKey,
 	Result,
+	assert,
 	assertExists,
 	exhaustiveSwitchError,
 	getOwnProperty,
 	hasOwnProperty,
+	isNativeStructuredClone,
 	objectMapEntries,
 	objectMapKeys,
 } from '@tldraw/utils'
@@ -208,6 +210,12 @@ export class TLSyncRoom<R extends UnknownRecord> {
 		public readonly schema: StoreSchema<R, any>,
 		snapshot?: RoomSnapshot
 	) {
+		assert(
+			isNativeStructuredClone,
+			'TLSyncRoom is supposed to run either on Cloudflare Workers' +
+				'or on a 18+ version of Node.js, which both support the native structuredClone API'
+		)
+
 		// do a json serialization cycle to make sure the schema has no 'undefined' values
 		this.serializedSchema = JSON.parse(JSON.stringify(schema.serialize()))
 

packages/utils/api-report.md

@@ -37,9 +37,6 @@ export function debounce<T extends unknown[], U>(callback: (...args: T) => Promi
 // @public
 export function dedupe<T>(input: T[], equals?: (a: any, b: any) => boolean): T[];
 
-// @public
-export function deepCopy<T = unknown>(obj: T): T;
-
 // @internal
 export function deleteFromLocalStorage(key: string): void;
 
@@ -140,6 +137,9 @@ export function invLerp(a: number, b: number, t: number): number;
 // @public
 export function isDefined<T>(value: T): value is typeof value extends undefined ? never : T;
 
+// @internal (undocumented)
+export const isNativeStructuredClone: boolean;
+
 // @public
 export function isNonNull<T>(value: T): value is typeof value extends null ? never : T;
 
@@ -307,6 +307,9 @@ export function sortByIndex<T extends {
     index: IndexKey;
 }>(a: T, b: T): -1 | 0 | 1;
 
+// @internal
+export const STRUCTURED_CLONE_OBJECT_PROTOTYPE: any;
+
 // @public
 const structuredClone_2: <T>(i: T) => T;
 export { structuredClone_2 as structuredClone }

packages/utils/api/api.json

@@ -357,72 +357,6 @@
           ],
           "name": "dedupe"
         },
-        {
-          "kind": "Function",
-          "canonicalReference": "@tldraw/utils!deepCopy:function(1)",
-          "docComment": "/**\n * Deep copy function for TypeScript.\n *\n * @param obj - Target value to be copied.\n *\n * @example\n * ```ts\n * const A = deepCopy({ a: 1, b: { c: 2 } })\n * ```\n *\n * @see\n *\n * Source - project, ts-deeply https://github.com/ykdr2017/ts-deepcopy\n *\n * @see\n *\n * Code - pen https://codepen.io/erikvullings/pen/ejyBYg\n *\n * @public\n */\n",
-          "excerptTokens": [
-            {
-              "kind": "Content",
-              "text": "export declare function deepCopy<T = "
-            },
-            {
-              "kind": "Content",
-              "text": "unknown"
-            },
-            {
-              "kind": "Content",
-              "text": ">(obj: "
-            },
-            {
-              "kind": "Content",
-              "text": "T"
-            },
-            {
-              "kind": "Content",
-              "text": "): "
-            },
-            {
-              "kind": "Content",
-              "text": "T"
-            },
-            {
-              "kind": "Content",
-              "text": ";"
-            }
-          ],
-          "fileUrlPath": "packages/utils/src/lib/object.ts",
-          "returnTypeTokenRange": {
-            "startIndex": 5,
-            "endIndex": 6
-          },
-          "releaseTag": "Public",
-          "overloadIndex": 1,
-          "parameters": [
-            {
-              "parameterName": "obj",
-              "parameterTypeTokenRange": {
-                "startIndex": 3,
-                "endIndex": 4
-              },
-              "isOptional": false
-            }
-          ],
-          "typeParameters": [
-            {
-              "typeParameterName": "T",
-              "constraintTokenRange": {
-                "startIndex": 0,
-                "endIndex": 0
-              },
-              "defaultTypeTokenRange": {
-                "startIndex": 1,
-                "endIndex": 2
-              }
-            }
-          ],
-          "name": "deepCopy"
-        },
         {
           "kind": "TypeAlias",
           "canonicalReference": "@tldraw/utils!ErrorResult:type",

packages/utils/package.json

@@ -50,6 +50,7 @@
 		}
 	},
 	"devDependencies": {
+		"jest-environment-jsdom": "^29.4.3",
 		"lazyrepo": "0.0.0-alpha.27"
 	}
 }

packages/utils/patchedJestJsDom.js

@@ -0,0 +1,10 @@
+import JSDOMEnvironment from 'jest-environment-jsdom'
+
+export default class FixJSDOMEnvironment extends JSDOMEnvironment {
+	constructor(...args) {
+		super(...args)
+
+		// fixes https://github.com/jsdom/jsdom/issues/3363
+		this.global.structuredClone = structuredClone
+	}
+}

packages/utils/src/index.ts

@@ -27,7 +27,6 @@ export { MediaHelpers } from './lib/media'
 export { invLerp, lerp, modulate, rng } from './lib/number'
 export {
 	areObjectsShallowEqual,
-	deepCopy,
 	filterEntries,
 	getOwnProperty,
 	hasOwnProperty,
@@ -64,5 +63,12 @@ export {
 } from './lib/storage'
 export { fpsThrottle, throttleToNextFrame } from './lib/throttle'
 export type { Expand, RecursivePartial, Required } from './lib/types'
-export { isDefined, isNonNull, isNonNullish, structuredClone } from './lib/value'
+export {
+	STRUCTURED_CLONE_OBJECT_PROTOTYPE,
+	isDefined,
+	isNativeStructuredClone,
+	isNonNull,
+	isNonNullish,
+	structuredClone,
+} from './lib/value'
 export { warnDeprecatedGetter } from './lib/warnDeprecatedGetter'

packages/utils/src/lib/object.ts

@@ -19,40 +19,6 @@ export function getOwnProperty(obj: object, key: string): unknown {
 	return obj[key]
 }
 
-/**
- * Deep copy function for TypeScript.
- *
- * @example
- *
- * ```ts
- * const A = deepCopy({ a: 1, b: { c: 2 } })
- * ```
- *
- * @param obj - Target value to be copied.
- * @public
- * @see Source - project, ts-deeply https://github.com/ykdr2017/ts-deepcopy
- * @see Code - pen https://codepen.io/erikvullings/pen/ejyBYg
- */
-export function deepCopy<T = unknown>(obj: T): T {
-	if (!obj) return obj
-	if (Array.isArray(obj)) {
-		const arr: unknown[] = []
-		const length = obj.length
-		for (let i = 0; i < length; i++) arr.push(deepCopy(obj[i]))
-		return arr as unknown as T
-	} else if (typeof obj === 'object') {
-		const keys = Object.keys(obj!)
-		const length = keys.length
-		const newObject: any = {}
-		for (let i = 0; i < length; i++) {
-			const key = keys[i]
-			newObject[key] = deepCopy((obj as any)[key])
-		}
-		return newObject
-	}
-	return obj
-}
-
 /**
  * An alias for `Object.keys` that treats the object as a map and so preserves the type of the keys.
  *

packages/utils/src/lib/value.ts

@@ -30,12 +30,44 @@ export function isNonNullish<T>(
 	return value !== null && value !== undefined
 }
 
+function getStructuredClone(): [<T>(i: T) => T, boolean] {
+	if (typeof globalThis !== 'undefined' && (globalThis as any).structuredClone) {
+		return [globalThis.structuredClone as <T>(i: T) => T, true]
+	}
+
+	if (typeof global !== 'undefined' && (global as any).structuredClone) {
+		return [global.structuredClone as <T>(i: T) => T, true]
+	}
+
+	if (typeof window !== 'undefined' && (window as any).structuredClone) {
+		return [window.structuredClone as <T>(i: T) => T, true]
+	}
+
+	return [<T>(i: T): T => (i ? JSON.parse(JSON.stringify(i)) : i), false]
+}
+
+const _structuredClone = getStructuredClone()
+
 /**
  * Create a deep copy of a value. Uses the structuredClone API if available, otherwise uses JSON.parse(JSON.stringify()).
  *
  * @param i - The value to clone.
  * @public */
-export const structuredClone =
-	typeof window !== 'undefined' && (window as any).structuredClone
-		? (window.structuredClone as <T>(i: T) => T)
-		: <T>(i: T): T => (i ? JSON.parse(JSON.stringify(i)) : i)
+export const structuredClone = _structuredClone[0]
+
+/**
+ * @internal
+ */
+export const isNativeStructuredClone = _structuredClone[1]
+
+/**
+ * When we patch structuredClone in jsdom for testing (see https://github.com/jsdom/jsdom/issues/3363),
+ * the Object that is used as a prototype for the cloned object is not the same as the Object in
+ * the code under test (that comes from jsdom's fake global context). This constant is used in
+ * our code to work around this case.
+ *
+ * This is also the case for Array prototype, but that problem can be worked around with an
+ * Array.isArray() check.
+ * @internal
+ */
+export const STRUCTURED_CLONE_OBJECT_PROTOTYPE = Object.getPrototypeOf(structuredClone({}))

packages/validate/src/lib/validation.ts

@@ -1,6 +1,7 @@
 import {
 	IndexKey,
 	JsonValue,
+	STRUCTURED_CLONE_OBJECT_PROTOTYPE,
 	exhaustiveSwitchError,
 	getOwnProperty,
 	hasOwnProperty,
@@ -698,7 +699,9 @@ function isPlainObject(value: unknown): value is Record<string, unknown> {
 	return (
 		typeof value === 'object' &&
 		value !== null &&
-		(value.constructor === Object || !value.constructor)
+		(Object.getPrototypeOf(value) === Object.prototype ||
+			Object.getPrototypeOf(value) === null ||
+			Object.getPrototypeOf(value) === STRUCTURED_CLONE_OBJECT_PROTOTYPE)
 	)
 }
 

scripts/prepack.ts

@@ -23,6 +23,7 @@ export async function preparePackage({ sourcePackageDir }: { sourcePackageDir: s
 	const cssFiles = glob.sync(path.join(sourcePackageDir, '*.css'))
 
 	// construct the final package.json
+	// eslint-disable-next-line no-restricted-globals
 	const newManifest = structuredClone({
 		// filter out comments
 		...Object.fromEntries(

yarn.lock

@@ -7188,6 +7188,7 @@ __metadata:
     "@microsoft/tsdoc": "npm:^0.14.2"
     "@radix-ui/react-accordion": "npm:^1.1.2"
     "@radix-ui/react-navigation-menu": "npm:^1.1.4"
+    "@tldraw/utils": "workspace:*"
     "@types/broken-link-checker": "npm:^0.7.1"
     "@types/node": "npm:~20.11"
     "@types/sqlite3": "npm:^3.1.9"
@@ -7463,6 +7464,7 @@ __metadata:
   version: 0.0.0-use.local
   resolution: "@tldraw/utils@workspace:packages/utils"
   dependencies:
+    jest-environment-jsdom: "npm:^29.4.3"
     lazyrepo: "npm:0.0.0-alpha.27"
   languageName: unknown
   linkType: soft