[feat] fs.watch (#3249)

* initial support

* add types

* fix comment

* fix types

* bigfix up

* more fixes

* fix some encoding support for watch

* fix rename event

* fixup

* fix latin1

* add fs_events, still failing some tests

* fixuup

* remove unecesary check

* readd tests ops

* this is necessary? just testing CI/CD weird errors

* just use dupe here

* cleanup and fix deinit

* fix zig upgrade

1 files changed, 64 insertions, 1 deletions

diff --git a/src/js/node/fs.js b/src/js/node/fs.js
index f117020dd..6b0e3954e 100644
--- a/src/js/node/fs.js
+++ b/src/js/node/fs.js
@@ -1,3 +1,5 @@
+import { EventEmitter } from "stream";
+
 // Hardcoded module "node:fs"
 var { direct, isPromise, isCallable } = import.meta.primordials;
 var promises = import.meta.require("node:fs/promises");
@@ -7,6 +9,63 @@ var NativeReadable = _getNativeReadableStreamPrototype(2, Readable); // 2 means
 
 var fs = Bun.fs();
 var debug = process.env.DEBUG ? console.log : () => {};
+
+class FSWatcher extends EventEmitter {
+  #watcher;
+  #listener;
+  constructor(path, options, listener) {
+    super();
+
+    if (typeof options === "function") {
+      listener = options;
+      options = {};
+    } else if (typeof options === "string") {
+      options = { encoding: options };
+    }
+
+    if (typeof listener !== "function") {
+      listener = () => {};
+    }
+
+    this.#listener = listener;
+    try {
+      this.#watcher = fs.watch(path, options || {}, this.#onEvent.bind(this));
+    } catch (e) {
+      if (!e.message?.startsWith("FileNotFound")) {
+        throw e;
+      }
+      const notFound = new Error(`ENOENT: no such file or directory, watch '${path}'`);
+      notFound.code = "ENOENT";
+      notFound.errno = -2;
+      notFound.path = path;
+      notFound.syscall = "watch";
+      notFound.filename = path;
+      throw notFound;
+    }
+  }
+
+  #onEvent(eventType, filenameOrError) {
+    if (eventType === "error" || eventType === "close") {
+      this.emit(eventType, filenameOrError);
+    } else {
+      this.emit("change", eventType, filenameOrError);
+      this.#listener(eventType, filenameOrError);
+    }
+  }
+
+  close() {
+    this.#watcher?.close();
+    this.#watcher = null;
+  }
+
+  ref() {
+    this.#watcher?.ref();
+  }
+
+  unref() {
+    this.#watcher?.unref();
+  }
+}
 export var access = function access(...args) {
     callbackify(fs.accessSync, args);
   },
@@ -153,6 +212,9 @@ export var access = function access(...args) {
   rmdirSync = fs.rmdirSync.bind(fs),
   Dirent = fs.Dirent,
   Stats = fs.Stats,
+  watch = function watch(path, options, listener) {
+    return new FSWatcher(path, options, listener);
+  },
   promises = import.meta.require("node:fs/promises");
 
 function callbackify(fsFunction, args) {
@@ -1002,7 +1064,8 @@ export default {
   writeSync,
   WriteStream,
   ReadStream,
-
+  watch,
+  FSWatcher,
   [Symbol.for("::bunternal::")]: {
     ReadStreamClass,
     WriteStreamClass,