fix(runtime): use more null proto objects (#23921)

This is a primordialization effort to improve resistance against users
tampering with the global `Object` prototype.

---------

Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

cli/js/40_jupyter.js

@@ -342,7 +342,7 @@ function enableJupyter() {
   async function broadcast(
     msgType,
     content,
-    { metadata = {}, buffers = [] } = {},
+    { metadata = { __proto__: null }, buffers = [] } = { __proto__: null },
   ) {
     await op_jupyter_broadcast(msgType, content, metadata, buffers);
   }
@@ -400,7 +400,7 @@ function enableJupyter() {
     if (options.update) {
       messageType = "update_display_data";
     }
-    let transient = {};
+    let transient = { __proto__: null };
     if (options.display_id) {
       transient = { display_id: options.display_id };
     }

cli/js/40_test.js

@@ -196,7 +196,7 @@ function testInner(
   nameOrFnOrOptions,
   optionsOrFn,
   maybeFn,
-  overrides = {},
+  overrides = { __proto__: null },
 ) {
   // No-op if we're not running in `deno test` subcommand.
   if (typeof op_register_test !== "function") {

ext/console/01_console.js

@@ -2930,7 +2930,7 @@ function cssToAnsi(css, prevCss = null) {
   return ansi;
 }
 
-function inspectArgs(args, inspectOptions = {}) {
+function inspectArgs(args, inspectOptions = { __proto__: null }) {
   const ctx = {
     ...getDefaultInspectOptions(),
     colors: inspectOptions.colors ?? !noColorStdout(),
@@ -3124,7 +3124,7 @@ class Console {
     );
   };
 
-  dir = (obj = undefined, options = {}) => {
+  dir = (obj = undefined, options = { __proto__: null }) => {
     this.#printFunc(
       inspectArgs([obj], {
         ...getConsoleInspectOptions(noColorStdout()),
@@ -3232,7 +3232,7 @@ class Console {
       resultData = [...new SafeSetIterator(data)];
     } else if (isMapObject) {
       let idx = 0;
-      resultData = {};
+      resultData = { __proto__: null };
 
       MapPrototypeForEach(data, (v, k) => {
         resultData[idx] = { Key: k, Values: v };
@@ -3390,7 +3390,7 @@ const customInspect = SymbolFor("Deno.customInspect");
 
 function inspect(
   value,
-  inspectOptions = {},
+  inspectOptions = { __proto__: null },
 ) {
   // Default options
   const ctx = {

ext/fetch/20_headers.js

@@ -100,7 +100,7 @@ function checkForInvalidValueChars(value) {
   return true;
 }
 
-let HEADER_NAME_CACHE = {};
+let HEADER_NAME_CACHE = { __proto__: null };
 let HEADER_CACHE_SIZE = 0;
 const HEADER_NAME_CACHE_SIZE_BOUNDARY = 4096;
 function checkHeaderNameForHttpTokenCodePoint(name) {
@@ -112,7 +112,7 @@ function checkHeaderNameForHttpTokenCodePoint(name) {
   const valid = RegExpPrototypeTest(HTTP_TOKEN_CODE_POINT_RE, name);
 
   if (HEADER_CACHE_SIZE > HEADER_NAME_CACHE_SIZE_BOUNDARY) {
-    HEADER_NAME_CACHE = {};
+    HEADER_NAME_CACHE = { __proto__: null };
     HEADER_CACHE_SIZE = 0;
   }
   HEADER_CACHE_SIZE++;
@@ -241,7 +241,7 @@ class Headers {
 
     // The order of steps are not similar to the ones suggested by the
     // spec but produce the same result.
-    const seenHeaders = {};
+    const seenHeaders = { __proto__: null };
     const entries = [];
     for (let i = 0; i < list.length; ++i) {
       const entry = list[i];

ext/fetch/23_request.js

@@ -300,7 +300,7 @@ class Request {
    * @param {RequestInfo} input
    * @param {RequestInit} init
    */
-  constructor(input, init = {}) {
+  constructor(input, init = { __proto__: null }) {
     if (input === _brand) {
       this[_brand] = _brand;
       return;

ext/fetch/23_response.js

@@ -282,7 +282,7 @@ class Response {
    * @param {ResponseInit} init
    * @returns {Response}
    */
-  static json(data = undefined, init = {}) {
+  static json(data = undefined, init = { __proto__: null }) {
     const prefix = "Failed to execute 'Response.json'";
     data = webidl.converters.any(data);
     init = webidl.converters["ResponseInit_fast"](init, prefix, "Argument 2");

ext/fetch/26_fetch.js

@@ -305,7 +305,7 @@ function httpRedirectFetch(request, response, terminator) {
  * @param {RequestInfo} input
  * @param {RequestInit} init
  */
-function fetch(input, init = {}) {
+function fetch(input, init = { __proto__: null }) {
   // There is an async dispatch later that causes a stack trace disconnect.
   // We reconnect it by assigning the result of that dispatch to `opPromise`,
   // awaiting `opPromise` in an inner function also named `fetch()` and

ext/fetch/27_eventsource.js

@@ -144,7 +144,7 @@ class EventSource extends EventTarget {
     return this.#withCredentials;
   }
 
-  constructor(url, eventSourceInitDict = {}) {
+  constructor(url, eventSourceInitDict = { __proto__: null }) {
     super();
     this[webidl.brand] = webidl.brand;
     const prefix = "Failed to construct 'EventSource'";

ext/ffi/00_ffi.js

@@ -475,7 +475,7 @@ const UnsafeCallbackPrototype = UnsafeCallback.prototype;
 
 class DynamicLibrary {
   #rid;
-  symbols = {};
+  symbols = { __proto__: null };
 
   constructor(path, symbols) {
     ({ 0: this.#rid, 1: this.symbols } = op_ffi_load({ path, symbols }));

ext/fs/30_fs.js

@@ -155,7 +155,7 @@ function chdir(directory) {
   op_fs_chdir(pathFromURL(directory));
 }
 
-function makeTempDirSync(options = {}) {
+function makeTempDirSync(options = { __proto__: null }) {
   return op_fs_make_temp_dir_sync(
     options.dir,
     options.prefix,
@@ -163,7 +163,7 @@ function makeTempDirSync(options = {}) {
   );
 }
 
-function makeTempDir(options = {}) {
+function makeTempDir(options = { __proto__: null }) {
   return op_fs_make_temp_dir_async(
     options.dir,
     options.prefix,
@@ -171,7 +171,7 @@ function makeTempDir(options = {}) {
   );
 }
 
-function makeTempFileSync(options = {}) {
+function makeTempFileSync(options = { __proto__: null }) {
   return op_fs_make_temp_file_sync(
     options.dir,
     options.prefix,
@@ -179,7 +179,7 @@ function makeTempFileSync(options = {}) {
   );
 }
 
-function makeTempFile(options = {}) {
+function makeTempFile(options = { __proto__: null }) {
   return op_fs_make_temp_file_async(
     options.dir,
     options.prefix,
@@ -241,7 +241,7 @@ function realPath(path) {
 
 function removeSync(
   path,
-  options = {},
+  options = { __proto__: null },
 ) {
   op_fs_remove_sync(
     pathFromURL(path),
@@ -251,7 +251,7 @@ function removeSync(
 
 async function remove(
   path,
-  options = {},
+  options = { __proto__: null },
 ) {
   await op_fs_remove_async(
     pathFromURL(path),
@@ -773,7 +773,7 @@ class FsFile {
     return core.isTerminal(this.#rid);
   }
 
-  setRaw(mode, options = {}) {
+  setRaw(mode, options = { __proto__: null }) {
     const cbreak = !!(options.cbreak ?? false);
     op_set_raw(this.#rid, mode, cbreak);
   }
@@ -889,7 +889,7 @@ async function readTextFile(path, options) {
 function writeFileSync(
   path,
   data,
-  options = {},
+  options = { __proto__: null },
 ) {
   options.signal?.throwIfAborted();
   op_fs_write_file_sync(
@@ -905,7 +905,7 @@ function writeFileSync(
 async function writeFile(
   path,
   data,
-  options = {},
+  options = { __proto__: null },
 ) {
   let cancelRid;
   let abortHandler;
@@ -951,7 +951,7 @@ async function writeFile(
 function writeTextFileSync(
   path,
   data,
-  options = {},
+  options = { __proto__: null },
 ) {
   const encoder = new TextEncoder();
   return writeFileSync(path, encoder.encode(data), options);
@@ -960,7 +960,7 @@ function writeTextFileSync(
 function writeTextFile(
   path,
   data,
-  options = {},
+  options = { __proto__: null },
 ) {
   if (ObjectPrototypeIsPrototypeOf(ReadableStreamPrototype, data)) {
     return writeFile(

ext/http/00_serve.ts

@@ -591,7 +591,7 @@ function serve(arg1, arg2) {
     throw new TypeError("A handler function must be provided.");
   }
   if (options === undefined) {
-    options = {};
+    options = { __proto__: null };
   }
 
   const wantsHttps = hasTlsKeyPairOptions(options);

ext/http/02_websocket.ts

@@ -37,7 +37,7 @@ const _ws = Symbol("[[associated_ws]]");
 const websocketCvf = buildCaseInsensitiveCommaValueFinder("websocket");
 const upgradeCvf = buildCaseInsensitiveCommaValueFinder("upgrade");
 
-function upgradeWebSocket(request, options = {}) {
+function upgradeWebSocket(request, options = { __proto__: null }) {
   const inner = toInnerRequest(request);
   const upgrade = request.headers.get("upgrade");
   const upgradeHasWebSocketOption = upgrade !== null &&

ext/io/12_io.js

@@ -228,7 +228,7 @@ class Stdin {
     return this.#readable;
   }
 
-  setRaw(mode, options = {}) {
+  setRaw(mode, options = { __proto__: null }) {
     const cbreak = !!(options.cbreak ?? false);
     op_set_raw(this.#rid, mode, cbreak);
   }

ext/kv/01_db.ts

@@ -210,7 +210,7 @@ class Kv {
       cursor?: string;
       reverse?: boolean;
       consistency?: Deno.KvConsistencyLevel;
-    } = {},
+    } = { __proto__: null },
   ): KvListIterator {
     if (options.limit !== undefined && options.limit <= 0) {
       throw new Error("limit must be positive");
@@ -340,7 +340,7 @@ class Kv {
     finishMessageOps.clear();
   }
 
-  watch(keys: Deno.KvKey[], options = {}) {
+  watch(keys: Deno.KvKey[], options = { __proto__: null }) {
     const raw = options.raw ?? false;
     const rid = op_kv_watch(this.#rid, keys);
     const lastEntries: (Deno.KvEntryMaybe<unknown> | undefined)[] = ArrayFrom(

ext/net/02_tls.js

@@ -281,7 +281,7 @@ async function startTls(
     hostname = "127.0.0.1",
     caCerts = [],
     alpnProtocols = undefined,
-  } = {},
+  } = { __proto__: null },
 ) {
   const { 0: rid, 1: localAddr, 2: remoteAddr } = op_tls_start({
     rid: conn[internalRidSymbol],

ext/web/02_event.js

@@ -123,7 +123,7 @@ const _isTrusted = Symbol("[[isTrusted]]");
 const _path = Symbol("[[path]]");
 
 class Event {
-  constructor(type, eventInitDict = {}) {
+  constructor(type, eventInitDict = { __proto__: null }) {
     // TODO(lucacasonato): remove when this interface is spec aligned
     this[SymbolToStringTag] = "Event";
     this[_canceledFlag] = false;
@@ -1095,7 +1095,7 @@ class ErrorEvent extends Event {
       lineno = 0,
       colno = 0,
       error,
-    } = {},
+    } = { __proto__: null },
   ) {
     super(type, {
       bubbles: bubbles,
@@ -1164,7 +1164,7 @@ class CloseEvent extends Event {
     wasClean = false,
     code = 0,
     reason = "",
-  } = {}) {
+  } = { __proto__: null }) {
     super(type, {
       bubbles: bubbles,
       cancelable: cancelable,
@@ -1238,7 +1238,7 @@ const MessageEventPrototype = MessageEvent.prototype;
 class CustomEvent extends Event {
   #detail = null;
 
-  constructor(type, eventInitDict = {}) {
+  constructor(type, eventInitDict = { __proto__: null }) {
     super(type, eventInitDict);
     webidl.requiredArguments(
       arguments.length,
@@ -1280,7 +1280,7 @@ ReflectDefineProperty(CustomEvent.prototype, "detail", {
 // ProgressEvent could also be used in other DOM progress event emits.
 // Current use is for FileReader.
 class ProgressEvent extends Event {
-  constructor(type, eventInitDict = {}) {
+  constructor(type, eventInitDict = { __proto__: null }) {
     super(type, eventInitDict);
 
     this.lengthComputable = eventInitDict?.lengthComputable ?? false;
@@ -1329,7 +1329,7 @@ class PromiseRejectionEvent extends Event {
       composed,
       promise,
       reason,
-    } = {},
+    } = { __proto__: null },
   ) {
     super(type, {
       bubbles: bubbles,

ext/web/06_streams.js

@@ -5274,7 +5274,7 @@ class ReadableStream {
         "Argument 1",
       );
     } else {
-      options = {};
+      options = { __proto__: null };
     }
     if (options.mode === undefined) {
       return acquireReadableStreamDefaultReader(this);
@@ -5290,7 +5290,7 @@ class ReadableStream {
    * @param {PipeOptions=} options
    * @returns {ReadableStream<T>}
    */
-  pipeThrough(transform, options = {}) {
+  pipeThrough(transform, options = { __proto__: null }) {
     webidl.assertBranded(this, ReadableStreamPrototype);
     const prefix = "Failed to execute 'pipeThrough' on 'ReadableStream'";
     webidl.requiredArguments(arguments.length, 1, prefix);
@@ -5329,7 +5329,7 @@ class ReadableStream {
    * @param {PipeOptions=} options
    * @returns {Promise<void>}
    */
-  pipeTo(destination, options = {}) {
+  pipeTo(destination, options = { __proto__: null }) {
     try {
       webidl.assertBranded(this, ReadableStreamPrototype);
       const prefix = "Failed to execute 'pipeTo' on 'ReadableStream'";
@@ -5567,7 +5567,7 @@ class ReadableStreamBYOBReader {
    * @param {ReadableStreamBYOBReaderReadOptions} options
    *  @returns {Promise<ReadableStreamBYOBReadResult>}
    */
-  read(view, options = {}) {
+  read(view, options = { __proto__: null }) {
     try {
       webidl.assertBranded(this, ReadableStreamBYOBReaderPrototype);
       const prefix = "Failed to execute 'read' on 'ReadableStreamBYOBReader'";
@@ -6151,8 +6151,8 @@ class TransformStream {
    */
   constructor(
     transformer = undefined,
-    writableStrategy = {},
-    readableStrategy = {},
+    writableStrategy = { __proto__: null },
+    readableStrategy = { __proto__: null },
   ) {
     const prefix = "Failed to construct 'TransformStream'";
     if (transformer !== undefined) {

ext/web/08_text_encoding.js

@@ -63,7 +63,7 @@ class TextDecoder {
    * @param {string} label
    * @param {TextDecoderOptions} options
    */
-  constructor(label = "utf-8", options = {}) {
+  constructor(label = "utf-8", options = { __proto__: null }) {
     const prefix = "Failed to construct 'TextDecoder'";
     label = webidl.converters.DOMString(label, prefix, "Argument 1");
     options = webidl.converters.TextDecoderOptions(
@@ -288,7 +288,7 @@ class TextDecoderStream {
    * @param {string} label
    * @param {TextDecoderOptions} options
    */
-  constructor(label = "utf-8", options = {}) {
+  constructor(label = "utf-8", options = { __proto__: null }) {
     const prefix = "Failed to construct 'TextDecoderStream'";
     label = webidl.converters.DOMString(label, prefix, "Argument 1");
     options = webidl.converters.TextDecoderOptions(

ext/web/09_file.js

@@ -223,7 +223,7 @@ class Blob {
    * @param {BlobPart[]} blobParts
    * @param {BlobPropertyBag} options
    */
-  constructor(blobParts = [], options = {}) {
+  constructor(blobParts = [], options = { __proto__: null }) {
     const prefix = "Failed to construct 'Blob'";
     blobParts = webidl.converters["sequence<BlobPart>"](
       blobParts,
@@ -500,7 +500,7 @@ class File extends Blob {
    * @param {string} fileName
    * @param {FilePropertyBag} options
    */
-  constructor(fileBits, fileName, options = {}) {
+  constructor(fileBits, fileName, options = { __proto__: null }) {
     const prefix = "Failed to construct 'File'";
     webidl.requiredArguments(arguments.length, 2, prefix);
 

ext/web/13_message_port.js

@@ -150,7 +150,7 @@ class MessagePort extends EventTarget {
    * @param {any} message
    * @param {object[] | StructuredSerializeOptions} transferOrOptions
    */
-  postMessage(message, transferOrOptions = {}) {
+  postMessage(message, transferOrOptions = { __proto__: null }) {
     webidl.assertBranded(this, MessagePortPrototype);
     const prefix = "Failed to execute 'postMessage' on 'MessagePort'";
     webidl.requiredArguments(arguments.length, 1, prefix);

ext/web/15_performance.js

@@ -234,7 +234,7 @@ class PerformanceMark extends PerformanceEntry {
 
   constructor(
     name,
-    options = {},
+    options = { __proto__: null },
   ) {
     const prefix = "Failed to construct 'PerformanceMark'";
     webidl.requiredArguments(arguments.length, 1, prefix);
@@ -441,7 +441,7 @@ class Performance extends EventTarget {
 
   mark(
     markName,
-    markOptions = {},
+    markOptions = { __proto__: null },
   ) {
     webidl.assertBranded(this, PerformancePrototype);
     const prefix = "Failed to execute 'mark' on 'Performance'";
@@ -466,7 +466,7 @@ class Performance extends EventTarget {
 
   measure(
     measureName,
-    startOrMeasureOptions = {},
+    startOrMeasureOptions = { __proto__: null },
     endMark = undefined,
   ) {
     webidl.assertBranded(this, PerformancePrototype);

ext/webgpu/01_webgpu.js

@@ -358,7 +358,7 @@ class GPU {
    * @param {GPURequestAdapterOptions} options
    */
   // deno-lint-ignore require-await
-  async requestAdapter(options = {}) {
+  async requestAdapter(options = { __proto__: null }) {
     webidl.assertBranded(this, GPUPrototype);
     options = webidl.converters.GPURequestAdapterOptions(
       options,
@@ -449,7 +449,7 @@ class GPUAdapter {
    * @returns {Promise<GPUDevice>}
    */
   // deno-lint-ignore require-await
-  async requestDevice(descriptor = {}) {
+  async requestDevice(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPUAdapterPrototype);
     const prefix = "Failed to execute 'requestDevice' on 'GPUAdapter'";
     descriptor = webidl.converters.GPUDeviceDescriptor(
@@ -1174,7 +1174,7 @@ class GPUDevice extends EventTarget {
    * @param {GPUSamplerDescriptor} descriptor
    * @returns {GPUSampler}
    */
-  createSampler(descriptor = {}) {
+  createSampler(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPUDevicePrototype);
     const prefix = "Failed to execute 'createSampler' on 'GPUDevice'";
     descriptor = webidl.converters.GPUSamplerDescriptor(
@@ -1687,7 +1687,7 @@ class GPUDevice extends EventTarget {
    * @param {GPUCommandEncoderDescriptor} descriptor
    * @returns {GPUCommandEncoder}
    */
-  createCommandEncoder(descriptor = {}) {
+  createCommandEncoder(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPUDevicePrototype);
     const prefix = "Failed to execute 'createCommandEncoder' on 'GPUDevice'";
     descriptor = webidl.converters.GPUCommandEncoderDescriptor(
@@ -1842,7 +1842,7 @@ defineEventHandler(GPUDevice.prototype, "uncapturederror");
 class GPUPipelineError extends DOMException {
   #reason;
 
-  constructor(message = "", options = {}) {
+  constructor(message = "", options = { __proto__: null }) {
     const prefix = "Failed to construct 'GPUPipelineError'";
     message = webidl.converters.DOMString(message, prefix, "Argument 1");
     options = webidl.converters.GPUPipelineErrorInit(
@@ -2499,7 +2499,7 @@ class GPUTexture {
   /**
    * @param {GPUTextureViewDescriptor} descriptor
    */
-  createView(descriptor = {}) {
+  createView(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPUTexturePrototype);
     const prefix = "Failed to execute 'createView' on 'GPUTexture'";
     webidl.requiredArguments(arguments.length, 0, prefix);
@@ -3306,7 +3306,7 @@ class GPUCommandEncoder {
   /**
    * @param {GPUComputePassDescriptor} descriptor
    */
-  beginComputePass(descriptor = {}) {
+  beginComputePass(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPUCommandEncoderPrototype);
     const prefix =
       "Failed to execute 'beginComputePass' on 'GPUCommandEncoder'";
@@ -3757,7 +3757,7 @@ class GPUCommandEncoder {
    * @param {GPUCommandBufferDescriptor} descriptor
    * @returns {GPUCommandBuffer}
    */
-  finish(descriptor = {}) {
+  finish(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPUCommandEncoderPrototype);
     const prefix = "Failed to execute 'finish' on 'GPUCommandEncoder'";
     descriptor = webidl.converters.GPUCommandBufferDescriptor(
@@ -4774,7 +4774,7 @@ class GPURenderBundleEncoder {
   /**
    * @param {GPURenderBundleDescriptor} descriptor
    */
-  finish(descriptor = {}) {
+  finish(descriptor = { __proto__: null }) {
     webidl.assertBranded(this, GPURenderBundleEncoderPrototype);
     const prefix = "Failed to execute 'finish' on 'GPURenderBundleEncoder'";
     descriptor = webidl.converters.GPURenderBundleDescriptor(

ext/webidl/00_webidl.js

@@ -192,7 +192,12 @@ function createIntegerConversion(bitLength, typeOpts) {
   const twoToTheBitLength = MathPow(2, bitLength);
   const twoToOneLessThanTheBitLength = MathPow(2, bitLength - 1);
 
-  return (V, prefix = undefined, context = undefined, opts = {}) => {
+  return (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) => {
     let x = toNumber(V);
     x = censorNegativeZero(x);
 
@@ -251,7 +256,12 @@ function createLongLongConversion(bitLength, { unsigned }) {
   const lowerBound = unsigned ? 0 : NumberMIN_SAFE_INTEGER;
   const asBigIntN = unsigned ? BigIntAsUintN : BigIntAsIntN;
 
-  return (V, prefix = undefined, context = undefined, opts = {}) => {
+  return (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) => {
     let x = toNumber(V);
     x = censorNegativeZero(x);
 
@@ -386,7 +396,12 @@ converters["unrestricted double"] = (V, _prefix, _context, _opts) => {
   return x;
 };
 
-converters.DOMString = function (V, prefix, context, opts = {}) {
+converters.DOMString = function (
+  V,
+  prefix,
+  context,
+  opts = { __proto__: null },
+) {
   if (typeof V === "string") {
     return V;
   } else if (V === null && opts.treatNullAsEmptyString) {
@@ -464,7 +479,7 @@ converters.ArrayBuffer = (
   V,
   prefix = undefined,
   context = undefined,
-  opts = {},
+  opts = { __proto__: null },
 ) => {
   if (!isArrayBuffer(V)) {
     if (opts.allowShared && !isSharedArrayBuffer(V)) {
@@ -490,7 +505,7 @@ converters.DataView = (
   V,
   prefix = undefined,
   context = undefined,
-  opts = {},
+  opts = { __proto__: null },
 ) => {
   if (!isDataView(V)) {
     throw makeException(
@@ -539,7 +554,7 @@ ArrayPrototypeForEach(
       V,
       prefix = undefined,
       context = undefined,
-      opts = {},
+      opts = { __proto__: null },
     ) => {
       if (TypedArrayPrototypeGetSymbolToStringTag(V) !== name) {
         throw makeException(
@@ -572,7 +587,7 @@ converters.ArrayBufferView = (
   V,
   prefix = undefined,
   context = undefined,
-  opts = {},
+  opts = { __proto__: null },
 ) => {
   if (!ArrayBufferIsView(V)) {
     throw makeException(
@@ -604,7 +619,7 @@ converters.BufferSource = (
   V,
   prefix = undefined,
   context = undefined,
-  opts = {},
+  opts = { __proto__: null },
 ) => {
   if (ArrayBufferIsView(V)) {
     let buffer;
@@ -722,7 +737,7 @@ function createDictionaryConverter(name, ...dictionaries) {
     return a.key < b.key ? -1 : 1;
   });
 
-  const defaultValues = {};
+  const defaultValues = { __proto__: null };
   for (let i = 0; i < allMembers.length; ++i) {
     const member = allMembers[i];
     if (ReflectHas(member, "defaultValue")) {
@@ -747,7 +762,12 @@ function createDictionaryConverter(name, ...dictionaries) {
     }
   }
 
-  return function (V, prefix = undefined, context = undefined, opts = {}) {
+  return function (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) {
     const typeV = type(V);
     switch (typeV) {
       case "Undefined":
@@ -812,7 +832,12 @@ function createDictionaryConverter(name, ...dictionaries) {
 function createEnumConverter(name, values) {
   const E = new SafeSet(values);
 
-  return function (V, prefix = undefined, _context = undefined, _opts = {}) {
+  return function (
+    V,
+    prefix = undefined,
+    _context = undefined,
+    _opts = { __proto__: null },
+  ) {
     const S = String(V);
 
     if (!E.has(S)) {
@@ -828,7 +853,12 @@ function createEnumConverter(name, values) {
 }
 
 function createNullableConverter(converter) {
-  return (V, prefix = undefined, context = undefined, opts = {}) => {
+  return (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) => {
     // FIXME: If Type(V) is not Object, and the conversion to an IDL value is
     // being performed due to V being assigned to an attribute whose type is a
     // nullable callback function that is annotated with
@@ -842,7 +872,12 @@ function createNullableConverter(converter) {
 
 // https://heycam.github.io/webidl/#es-sequence
 function createSequenceConverter(converter) {
-  return function (V, prefix = undefined, context = undefined, opts = {}) {
+  return function (
+    V,
+    prefix = undefined,
+    context = undefined,
+    opts = { __proto__: null },
+  ) {
     if (type(V) !== "Object") {
       throw makeException(
         TypeError,
@@ -894,7 +929,7 @@ function createRecordConverter(keyConverter, valueConverter) {
         context,
       );
     }
-    const result = {};
+    const result = { __proto__: null };
     // Fast path for common case (not a Proxy)
     if (!core.isProxy(V)) {
       for (const key in V) {

ext/websocket/02_websocketstream.js

@@ -474,7 +474,7 @@ class WebSocketError extends DOMException {
   #closeCode;
   #reason;
 
-  constructor(message = "", init = {}) {
+  constructor(message = "", init = { __proto__: null }) {
     super(message, "WebSocketError");
     this[webidl.brand] = webidl.brand;
 

runtime/js/10_permissions.js

@@ -268,7 +268,7 @@ const permissions = new Permissions(illegalConstructorKey);
 /** Converts all file URLs in FS allowlists to paths. */
 function serializePermissions(permissions) {
   if (typeof permissions == "object" && permissions != null) {
-    const serializedPermissions = {};
+    const serializedPermissions = { __proto__: null };
     for (
       const key of new SafeArrayIterator(["read", "write", "run", "ffi"])
     ) {

runtime/js/11_workers.js

@@ -91,7 +91,7 @@ class Worker extends EventTarget {
   // still be messages left to receive.
   #status = "RUNNING";
 
-  constructor(specifier, options = {}) {
+  constructor(specifier, options = { __proto__: null }) {
     super();
     specifier = String(specifier);
     const {
@@ -254,7 +254,7 @@ class Worker extends EventTarget {
     }
   };
 
-  postMessage(message, transferOrOptions = {}) {
+  postMessage(message, transferOrOptions = { __proto__: null }) {
     const prefix = "Failed to execute 'postMessage' on 'MessagePort'";
     webidl.requiredArguments(arguments.length, 1, prefix);
     message = webidl.converters.any(message);

runtime/js/40_process.js

@@ -134,7 +134,7 @@ function run({
   cmd,
   cwd = undefined,
   clearEnv = false,
-  env = {},
+  env = { __proto__: null },
   gid = undefined,
   uid = undefined,
   stdout = "inherit",
@@ -172,7 +172,7 @@ function spawnChildInner(opFn, command, apiName, {
   args = [],
   cwd = undefined,
   clearEnv = false,
-  env = {},
+  env = { __proto__: null },
   uid = undefined,
   gid = undefined,
   stdin = "null",
@@ -181,7 +181,7 @@ function spawnChildInner(opFn, command, apiName, {
   signal = undefined,
   windowsRawArguments = false,
   ipc = -1,
-} = {}) {
+} = { __proto__: null }) {
   const child = opFn({
     cmd: pathFromURL(command),
     args: ArrayPrototypeMap(args, String),
@@ -202,7 +202,7 @@ function spawnChildInner(opFn, command, apiName, {
   });
 }
 
-function spawnChild(command, options = {}) {
+function spawnChild(command, options = { __proto__: null }) {
   return spawnChildInner(
     op_spawn_child,
     command,
@@ -392,14 +392,14 @@ function spawnSync(command, {
   args = [],
   cwd = undefined,
   clearEnv = false,
-  env = {},
+  env = { __proto__: null },
   uid = undefined,
   gid = undefined,
   stdin = "null",
   stdout = "piped",
   stderr = "piped",
   windowsRawArguments = false,
-} = {}) {
+} = { __proto__: null }) {
   if (stdin === "piped") {
     throw new TypeError(
       "Piped stdin is not supported for this function, use 'Deno.Command().spawn()' instead",

runtime/js/40_signals.js

@@ -26,7 +26,7 @@ function unbindSignal(rid) {
 
 // Stores signal listeners and resource data. This has type of
 // `Record<string, { rid: number | undefined, listeners: Set<() => void> }`
-const signalData = {};
+const signalData = { __proto__: null };
 
 /** Gets the signal handlers and resource data of the given signal */
 function getSignalData(signo) {

runtime/js/90_deno_ns.js

@@ -264,9 +264,9 @@ const unstableIds = {
   workerOptions: 11,
 };
 
-const denoNsUnstableById = {};
+const denoNsUnstableById = { __proto__: null };
 
-// denoNsUnstableById[unstableIds.broadcastChannel] = {}
+// denoNsUnstableById[unstableIds.broadcastChannel] = { __proto__: null }
 
 denoNsUnstableById[unstableIds.cron] = {
   cron: cron.cron,
@@ -308,13 +308,13 @@ denoNsUnstableById[unstableIds.net] = {
   ),
 };
 
-// denoNsUnstableById[unstableIds.unsafeProto] = {}
+// denoNsUnstableById[unstableIds.unsafeProto] = { __proto__: null }
 
 denoNsUnstableById[unstableIds.webgpu] = {
   UnsafeWindowSurface: webgpuSurface.UnsafeWindowSurface,
 };
 
-// denoNsUnstableById[unstableIds.workerOptions] = {}
+// denoNsUnstableById[unstableIds.workerOptions] = { __proto__: null }
 
 // when editing this list, also update unstableDenoProps in cli/tsc/99_main_compiler.js
 const denoNsUnstable = {

runtime/js/98_global_scope_shared.js

@@ -145,7 +145,7 @@ const windowOrWorkerGlobalScope = {
   [webidl.brand]: core.propNonEnumerable(webidl.brand),
 };
 
-const unstableForWindowOrWorkerGlobalScope = {};
+const unstableForWindowOrWorkerGlobalScope = { __proto__: null };
 unstableForWindowOrWorkerGlobalScope[unstableIds.broadcastChannel] = {
   BroadcastChannel: core.propNonEnumerable(broadcastChannel.BroadcastChannel),
 };

runtime/js/99_main.js

@@ -252,7 +252,7 @@ function workerClose() {
   op_worker_close();
 }
 
-function postMessage(message, transferOrOptions = {}) {
+function postMessage(message, transferOrOptions = { __proto__: null }) {
   const prefix =
     "Failed to execute 'postMessage' on 'DedicatedWorkerGlobalScope'";
   webidl.requiredArguments(arguments.length, 1, prefix);

tests/unit/event_test.ts

@@ -141,3 +141,17 @@ Deno.test(function inspectEvent() {
     `Event {\n  bubbles: false,\n  cancelable: false,`,
   );
 });
+
+Deno.test("default argument is null prototype", () => {
+  const event = new Event("test");
+  assertEquals(event.bubbles, false);
+
+  // @ts-ignore this is on purpose to check if overriding prototype
+  // has effect on `Event.
+  Object.prototype.bubbles = true;
+  const event2 = new Event("test");
+  assertEquals(event2.bubbles, false);
+
+  // @ts-ignore this is done on purpose
+  delete Object.prototype.bubbles;
+});