FileSystemFileHandle.createWritable()
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The createWritable()
method of the
FileSystemFileHandle
interface creates
a FileSystemWritableFileStream
that can be used to write to a file.
The method returns a Promise
which resolves to this created stream.
Any changes made through the stream won't be reflected in the file represented by the file handle until the stream has been closed. This is typically implemented by writing data to a temporary file, and only replacing the file represented by file handle with the temporary file when the writable filestream is closed.
Syntax
const fileStreamPromise = FileSystemFileHandle.createWritable();
Parameters
- FileSystemCreateWritableOptions
-
An object representing options to pass into the method. Options are:
-
keepExistingData
: Iffalse
or not specified, the temporary file starts out empty, otherwise the existing file is first copied to this temporary file.
-
Return value
A Promise
which resolves to a FileSystemWritableFileStream
object.
Exceptions
- NotAllowedError
-
Thrown if the
PermissionStatus.state
for the handle is not'granted'
inreadwrite
mode.
Examples
The following asynchronous function writes the given contents to the file handle, and thus to disk.
async function writeFile(fileHandle, contents) {
// Create a FileSystemWritableFileStream to write to.
const writable = await fileHandle.createWritable();
// Write the contents of the file to the stream.
await writable.write(contents);
// Close the file and write the contents to disk.
await writable.close();
}
Specifications
Specification |
---|
File System Access # api-filesystemfilehandle-createwritable |
Browser compatibility
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