Table of Contents

Class FileSystemSyncAccessHandle

Namespace
CSharpToJavaScript.APIs.JS
Assembly
CSharpToJavaScript.dll

The FileSystemSyncAccessHandle interface of the {{domxref("File System API", "File System API", "", "nocode")}} represents a synchronous handle to a file system entry.

[Value("FileSystemSyncAccessHandle")]
public class FileSystemSyncAccessHandle
Inheritance
FileSystemSyncAccessHandle
Inherited Members

Remarks

This class is only accessible inside dedicated Web Workers (so that its methods do not block execution on the main thread) for files within the origin private file system, which is not visible to end-users.

As a result, its methods are not subject to the same security checks as methods running on files within the user-visible file system, and so are much more performant. This makes them suitable for significant, large-scale file updates such as SQLite database modifications.

The interface is accessed through the 'FileSystemFileHandle.CreateSyncAccessHandle' method.

NOTE

In earlier versions of the spec, Close(), Flush(), GetSize(), and Truncate(ulong) 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.

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

Constructors

FileSystemSyncAccessHandle() 

public FileSystemSyncAccessHandle()

Methods

Close()

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.

[Value("close")]
public GlobalObject.Undefined Close()

Returns

GlobalObject.Undefined

None ('undefined').

Remarks

NOTE

In earlier versions of the spec, close(), Flush(), GetSize(), and Truncate(ulong) 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.

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

Flush()

The flush() method of the
FileSystemSyncAccessHandle interface persists any changes made to the file associated with the handle via the 'FileSystemSyncAccessHandle.Write' method to disk.

[Value("flush")]
public GlobalObject.Undefined Flush()

Returns

GlobalObject.Undefined

None ('undefined').

Remarks

Bear in mind that you only need to call this method if you need the changes committed to disk at a specific time, otherwise you can leave the underlying operating system to handle this when it sees fit, which should be OK in most cases.

NOTE

In earlier versions of the spec, Close(), flush(), GetSize(), and Truncate(ulong) 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.

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

GetSize()

The getSize() method of the
FileSystemSyncAccessHandle interface returns the size of the file associated with the handle in bytes.

[Value("getSize")]
public ulong GetSize()

Returns

ulong

A number representing the size of the file in bytes.

Remarks

NOTE

In earlier versions of the spec, Close(), Flush(), getSize(), and Truncate(ulong) 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.

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

Read(Union225, FileSystemReadWriteOptions)

The read() method of the
FileSystemSyncAccessHandle interface reads the content of the file associated with the handle into a specified buffer, optionally at a given offset.

[Value("read")]
public ulong Read(Union225 buffer, FileSystemReadWriteOptions options = null)

Parameters

buffer Union225
options FileSystemReadWriteOptions

Returns

ulong

A number representing the number of bytes read from the file.

Remarks

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

Truncate(ulong)

The truncate() method of the
FileSystemSyncAccessHandle interface resizes the file associated with the handle to a specified number of bytes.

[Value("truncate")]
public GlobalObject.Undefined Truncate(ulong newSize)

Parameters

newSize ulong

Returns

GlobalObject.Undefined

None ('undefined').

Remarks

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.

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

Write(Union225, FileSystemReadWriteOptions)

The write() method of the
FileSystemSyncAccessHandle interface writes the content of a specified buffer to the file associated with the handle, optionally at a given offset.

[Value("write")]
public ulong Write(Union225 buffer, FileSystemReadWriteOptions options = null)

Parameters

buffer Union225
options FileSystemReadWriteOptions

Returns

ulong

A number representing the number of bytes written to the file.

Remarks

Files within the origin private file system are not visible to end-users, therefore are not subject to the same security checks as methods running on files within the user-visible file system. As a result, writes performed using FileSystemSyncAccessHandle.write() are much more performant. This makes them suitable for significant, large-scale file updates such as SQLite database modifications.

-File System API
-The File System Access API: simplifying access to local files

See also on MDN

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