FileSystemSyncAccessHandle: close() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2023.

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

Note: This feature is only available in Dedicated Web Workers.

The close() method of the FileSystemSyncAccessHandle interface closes an open synchronous file handle, disabling any further operations on it and releasing the exclusive lock previously put on the file associated with the file handle.

Note: In earlier versions of the spec, close(), flush(), getSize(), and truncate() were wrongly specified as asynchronous methods, and older versions of some browsers implement them in this way. However, all current browsers that support these methods implement them as synchronous methods.

Syntax

js
close()

Parameters

None.

Return value

None (undefined).

Exceptions

None.

Examples

The following asynchronous event handler function is contained inside a Web Worker. On receiving a message from the main thread it:

  • Creates a synchronous file access handle.
  • Gets the size of the file and creates an ArrayBuffer to contain it.
  • Reads the file contents into the buffer.
  • Encodes the message and writes it to the end of the file.
  • Persists the changes to disk and closes the access handle.
js
onmessage = async (e) => {
  // Retrieve message sent to work from main script
  const message = e.data;

  // Get handle to draft file
  const root = await navigator.storage.getDirectory();
  const draftHandle = await root.getFileHandle("draft.txt", { create: true });
  // Get sync access handle
  const accessHandle = await draftHandle.createSyncAccessHandle();

  // Get size of the file.
  const fileSize = accessHandle.getSize();
  // Read file content to a buffer.
  const buffer = new DataView(new ArrayBuffer(fileSize));
  const readBuffer = accessHandle.read(buffer, { at: 0 });

  // Write the message to the end of the file.
  const encoder = new TextEncoder();
  const encodedMessage = encoder.encode(message);
  const writeBuffer = accessHandle.write(encodedMessage, { at: readBuffer });

  // Persist changes to disk.
  accessHandle.flush();

  // Always close FileSystemSyncAccessHandle if done.
  accessHandle.close();
};

Specifications

Specification
File System
# api-filesystemsyncaccesshandle-close

Browser compatibility

desktop mobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
close
Chrome – Full support
Chrome 102 (Release date: 2022-05-24)
footnote Full support
Edge – Full support
Edge 102 (Release date: 2022-05-31)
footnote Full support
Firefox – Full support
Firefox 111 (Release date: 2023-03-14)
footnote Full support
Opera – Full support
Opera 88 (Release date: 2022-06-08)
footnote Full support
Safari – Full support
Safari 15.2 (Release date: 2021-12-13)
footnote Full support
Chrome Android – Full support
Chrome Android 109 (Release date: 2023-01-10)
footnote Full support
Firefox for Android – Full support
Firefox for Android 111 (Release date: 2023-03-14)
footnote Full support
Opera Android – Full support
Opera Android 74 (Release date: 2023-03-13)
footnote Full support
Safari on iOS – Full support
Safari on iOS 15.2 (Release date: 2021-12-13)
footnote Full support
Samsung Internet – Full support
Samsung Internet 21 (Release date: 2023-05-19)
footnote Full support
WebView Android – Full support
WebView Android 109 (Release date: 2023-01-10)
footnote Full support
WebView on iOS – Full support
WebView on iOS 15.2 (Release date: 2021-12-13)
footnote Full support
Synchronous implementation of the close() method
Chrome – Full support
Chrome 108 (Release date: 2022-11-29)
footnote Full support
Edge – Full support
Edge 108 (Release date: 2022-12-05)
footnote Full support
Firefox – Full support
Firefox 111 (Release date: 2023-03-14)
footnote Full support
Opera – Full support
Opera 94 (Release date: 2022-12-15)
footnote Full support
Safari – Full support
Safari 16.4 (Release date: 2023-03-27)
footnote Full support
Chrome Android – Full support
Chrome Android 109 (Release date: 2023-01-10)
footnote Full support
Firefox for Android – Full support
Firefox for Android 111 (Release date: 2023-03-14)
footnote Full support
Opera Android – Full support
Opera Android 74 (Release date: 2023-03-13)
footnote Full support
Safari on iOS – Full support
Safari on iOS 16.4 (Release date: 2023-03-27)
footnote Full support
Samsung Internet – Full support
Samsung Internet 21 (Release date: 2023-05-19)
footnote Full support
WebView Android – Full support
WebView Android 109 (Release date: 2023-01-10)
footnote Full support
WebView on iOS – Full support
WebView on iOS 16.4 (Release date: 2023-03-27)
footnote Full support

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also