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Title: FileSystemObserver - Web APIs | MDN

Open Graph Title: FileSystemObserver - Web APIs | MDN

Description: The FileSystemObserver interface of the File System API provides a mechanism to observe changes to the user-observable file system and the Origin Private File System (OPFS). This means web applications don't have to poll the file system to find changes in the files or folder structure, which can be time-consuming and wasteful.

Open Graph Description: The FileSystemObserver interface of the File System API provides a mechanism to observe changes to the user-observable file system and the Origin Private File System (OPFS). This means web applications don't have to poll the file system to find changes in the files or folder structure, which can be time-consuming and wasteful.

Opengraph URL: https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver

direct link

Domain: developer.mozilla.org

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Links:

Skip to main contenthttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#content
Skip to searchhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#search
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FileSystemObserverhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver
https://github.com/orgs/mdn/discussions/739
https://developer.mozilla.org/de/docs/Web/API/FileSystemObserver
https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver
https://developer.mozilla.org/zh-CN/docs/Web/API/FileSystemObserver
secure contextshttps://developer.mozilla.org/en-US/docs/Web/Security/Defenses/Secure_Contexts
supporting browsershttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#browser_compatibility
experimental technologyhttps://developer.mozilla.org/en-US/docs/MDN/Writing_guidelines/Experimental_deprecated_obsolete#experimental
Browser compatibility tablehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#browser_compatibility
File System APIhttps://developer.mozilla.org/en-US/docs/Web/API/File_System_API
Origin Private File Systemhttps://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system
Constructorhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#constructor
Instance methodshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#instance_methods
Exampleshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#examples
Specificationshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#specifications
Browser compatibilityhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#browser_compatibility
See alsohttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#see_also
Constructorhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#constructor
FileSystemObserver()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/FileSystemObserver
Instance methodshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#instance_methods
disconnect()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/disconnect
observe()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/observe
Exampleshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#examples
File System Observer Demohttps://mdn.github.io/dom-examples/file-system-api/filesystemobserver/
source codehttps://github.com/mdn/dom-examples/tree/main/file-system-api/filesystemobserver
Initialize a FileSystemObserverhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#initialize_a_filesystemobserver
FileSystemObserver()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/FileSystemObserver
callback functionhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/FileSystemObserver#callback
Observe a file or directoryhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#observe_a_file_or_directory
FileSystemObserver.observe()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/observe
Origin Private File Systemhttps://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system
FileSystemFileHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemFileHandle
FileSystemDirectoryHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemDirectoryHandle
Window.showSaveFilePicker()https://developer.mozilla.org/en-US/docs/Web/API/Window/showSaveFilePicker
Window.showDirectoryPicker()https://developer.mozilla.org/en-US/docs/Web/API/Window/showDirectoryPicker
FileSystemSyncAccessHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemSyncAccessHandle
Stop observing the file systemhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#stop_observing_the_file_system
FileSystemObserver.disconnect()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/disconnect
Specificationshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#specifications
https://github.com/whatwg/fs/pull/165https://github.com/whatwg/fs/pull/165
Browser compatibilityhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#browser_compatibility
See alsohttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver#see_also
File System APIhttps://developer.mozilla.org/en-US/docs/Web/API/File_System_API
The File System Observer API origin trialhttps://developer.chrome.com/blog/file-system-observer#stop-observing-the-file-system
Learn how to contributehttps://developer.mozilla.org/en-US/docs/MDN/Community/Getting_started
MDN contributorshttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/contributors.txt
View this page on GitHubhttps://github.com/mdn/content/blob/main/files/en-us/web/api/filesystemobserver/index.md?plain=1
Report a problem with this contenthttps://github.com/mdn/content/issues/new?template=page-report.yml&mdn-url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAPI%2FFileSystemObserver&metadata=%3C%21--+Do+not+make+changes+below+this+line+--%3E%0A%3Cdetails%3E%0A%3Csummary%3EPage+report+details%3C%2Fsummary%3E%0A%0A*+Folder%3A+%60en-us%2Fweb%2Fapi%2Ffilesystemobserver%60%0A*+MDN+URL%3A+https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAPI%2FFileSystemObserver%0A*+GitHub+URL%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fblob%2Fmain%2Ffiles%2Fen-us%2Fweb%2Fapi%2Ffilesystemobserver%2Findex.md%0A*+Last+commit%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fcommit%2Fac7a39584dc77b42aac19473cc522bbedbf13717%0A*+Document+last+modified%3A+2025-07-04T19%3A29%3A27.000Z%0A%0A%3C%2Fdetails%3E
File System APIhttps://developer.mozilla.org/en-US/docs/Web/API/File_System_API
FileSystemObserverhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver
FileSystemObserver()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/FileSystemObserver
disconnect()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/disconnect
observe()https://developer.mozilla.org/en-US/docs/Web/API/FileSystemObserver/observe
DataTransferItem.getAsFileSystemHandle()https://developer.mozilla.org/en-US/docs/Web/API/DataTransferItem/getAsFileSystemHandle
FileSystemChangeRecordhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemChangeRecord
FileSystemDirectoryHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemDirectoryHandle
FileSystemFileHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemFileHandle
FileSystemHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemHandle
FileSystemSyncAccessHandlehttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemSyncAccessHandle
FileSystemWritableFileStreamhttps://developer.mozilla.org/en-US/docs/Web/API/FileSystemWritableFileStream
StorageManager.getDirectory()https://developer.mozilla.org/en-US/docs/Web/API/StorageManager/getDirectory
Window.showDirectoryPicker()https://developer.mozilla.org/en-US/docs/Web/API/Window/showDirectoryPicker
Window.showOpenFilePicker()https://developer.mozilla.org/en-US/docs/Web/API/Window/showOpenFilePicker
Window.showSaveFilePicker()https://developer.mozilla.org/en-US/docs/Web/API/Window/showSaveFilePicker
Origin private file systemhttps://developer.mozilla.org/en-US/docs/Web/API/File_System_API/Origin_private_file_system
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