FileSystemHandle: requestPermission() method

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The requestPermission() method of the FileSystemHandle interface requests read or readwrite permissions for the file handle.




descriptor Optional

An object which specifies the permission mode to query for. Options are as follows:

'mode' Optional

Can be either 'read' or 'readwrite'.

Return value

A Promise that resolves to a PermissionStatus object.



Thrown if no parameter is specified or the mode is not that of 'read' or 'readwrite'


The following asynchronous function requests permissions if they have not been granted.

// fileHandle is a FileSystemFileHandle
// withWrite is a boolean set to true if write

async function verifyPermission(fileHandle, withWrite) {
  const opts = {};
  if (withWrite) {
    opts.mode = "readwrite";

  // Check if we already have permission, if so, return true.
  if ((await fileHandle.queryPermission(opts)) === "granted") {
    return true;

  // Request permission to the file, if the user grants permission, return true.
  if ((await fileHandle.requestPermission(opts)) === "granted") {
    return true;

  // The user did not grant permission, return false.
  return false;


File System Access
# api-filesystemhandle-requestpermission

Browser compatibility

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See also