From cbba68fe79cbae39049b3ea8d7245466836ba229 Mon Sep 17 00:00:00 2001
From: Nathan Whitaker <nathan@deno.com>
Date: Mon, 27 Apr 2026 12:59:22 +0000
Subject: [PATCH 1/2] fix(ext/node): validate fs.watch options.ignore
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Match Node's `internal/validators.js#validateIgnoreOption` /
`validateIgnoreOptionElement`, used by `fs.watch` and
`fs/promises.watch`:

- Element must be string, RegExp, or function — otherwise
  `ERR_INVALID_ARG_TYPE`.
- An empty string raises `ERR_INVALID_ARG_VALUE` ("must be a non-empty
  string").
- Arrays validate each element; null/undefined are accepted as no-op.

Previously `fs.watch` silently accepted any value (numbers, empty
strings) and only later quietly ignored them.

Enables `parallel/test-fs-watch-ignore-invalid.js`.
---
 ext/node/polyfills/fs.ts       | 40 ++++++++++++++++++++++++++++++++++
 tests/node_compat/config.jsonc |  1 +
 2 files changed, 41 insertions(+)

diff --git a/ext/node/polyfills/fs.ts b/ext/node/polyfills/fs.ts
index 100359344dc6a0..609b0be6d5f91e 100644
--- a/ext/node/polyfills/fs.ts
+++ b/ext/node/polyfills/fs.ts
@@ -141,6 +141,7 @@ import {
 import {
   ERR_FS_RMDIR_ENOTDIR,
   ERR_INVALID_ARG_TYPE,
+  ERR_INVALID_ARG_VALUE,
   uvException,
 } from "ext:deno_node/internal/errors.ts";
 import { toUnixTimestamp } from "ext:deno_node/internal/fs/utils.mjs";
@@ -3159,10 +3160,47 @@ type watchOptions = {
   persistent?: boolean;
   recursive?: boolean;
   encoding?: string;
+  // deno-lint-ignore no-explicit-any
+  ignore?: string | RegExp | ((path: string) => boolean) | any[];
 };
 
 type watchListener = (eventType: string, filename: string) => void;
 
+// Mirrors Node's `validateIgnoreOption` /
+// `validateIgnoreOptionElement` in lib/internal/validators.js.
+// deno-lint-ignore no-explicit-any
+function validateIgnoreOptionElement(value: any, name: string) {
+  if (typeof value === "string") {
+    if (value.length === 0) {
+      throw new ERR_INVALID_ARG_VALUE(
+        name,
+        value,
+        "must be a non-empty string",
+      );
+    }
+    return;
+  }
+  if (value instanceof RegExp) return;
+  if (typeof value === "function") return;
+  throw new ERR_INVALID_ARG_TYPE(
+    name,
+    ["string", "RegExp", "Function"],
+    value,
+  );
+}
+
+// deno-lint-ignore no-explicit-any
+function validateIgnoreOption(value: any, name: string) {
+  if (value == null) return;
+  if (Array.isArray(value)) {
+    for (let i = 0; i < value.length; i++) {
+      validateIgnoreOptionElement(value[i], `${name}[${i}]`);
+    }
+    return;
+  }
+  validateIgnoreOptionElement(value, name);
+}
+
 function watch(
   filename: string | URL,
   options: watchOptions,
@@ -3193,6 +3231,8 @@ function watch(
     ? optionsOrListener2
     : undefined;
 
+  validateIgnoreOption(options?.ignore, "options.ignore");
+
   // deno-lint-ignore prefer-primordials
   const watchPath = getValidatedPath(filename).toString();
 
diff --git a/tests/node_compat/config.jsonc b/tests/node_compat/config.jsonc
index e810c46265d11e..0c3b2910fad4e7 100644
--- a/tests/node_compat/config.jsonc
+++ b/tests/node_compat/config.jsonc
@@ -1178,6 +1178,7 @@
     "parallel/test-fs-utimes-y2K38.js": {},
     "parallel/test-fs-utimes.js": {},
     "parallel/test-fs-watch-file-enoent-after-deletion.js": {},
+    "parallel/test-fs-watch-ignore-invalid.js": {},
     "parallel/test-fs-watch-recursive-add-file-to-existing-subfolder.js": {},
     "parallel/test-fs-watch-recursive-add-folder.js": {},
     "parallel/test-fs-watch-recursive-delete.js": {},

From 6508877833af12a7908b55646066af74ad0a054d Mon Sep 17 00:00:00 2001
From: Nathan Whitaker <nathan@deno.com>
Date: Mon, 27 Apr 2026 16:44:54 +0000
Subject: [PATCH 2/2] fix(ext/node): use primordials in fs.watch ignore
 validators

---
 ext/node/polyfills/fs.ts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/ext/node/polyfills/fs.ts b/ext/node/polyfills/fs.ts
index 609b0be6d5f91e..e51a1a35b79eec 100644
--- a/ext/node/polyfills/fs.ts
+++ b/ext/node/polyfills/fs.ts
@@ -158,6 +158,7 @@ import { core, primordials } from "ext:core/mod.js";
 
 const {
   ArrayBufferIsView,
+  ArrayIsArray,
   BigInt,
   DatePrototypeGetTime,
   DateUTC,
@@ -178,6 +179,7 @@ const {
   Promise,
   PromisePrototypeThen,
   PromiseResolve,
+  RegExpPrototype,
   SafeMap,
   StringPrototypeToString,
   SymbolAsyncIterator,
@@ -3180,7 +3182,7 @@ function validateIgnoreOptionElement(value: any, name: string) {
     }
     return;
   }
-  if (value instanceof RegExp) return;
+  if (ObjectPrototypeIsPrototypeOf(RegExpPrototype, value)) return;
   if (typeof value === "function") return;
   throw new ERR_INVALID_ARG_TYPE(
     name,
@@ -3192,7 +3194,7 @@ function validateIgnoreOptionElement(value: any, name: string) {
 // deno-lint-ignore no-explicit-any
 function validateIgnoreOption(value: any, name: string) {
   if (value == null) return;
-  if (Array.isArray(value)) {
+  if (ArrayIsArray(value)) {
     for (let i = 0; i < value.length; i++) {
       validateIgnoreOptionElement(value[i], `${name}[${i}]`);
     }