FileSystemSyncAccessHandle: close() method
Baseline 2023
Newly available
Since March 2023, this feature works across the latest devices and browser versions. This feature might not work in older devices or browsers.
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
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.
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 Standard # api-filesystemsyncaccesshandle-close |
Browser compatibility
BCD tables only load in the browser