FileSystemHandle: queryPermission() method

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Note: This feature is available in Web Workers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The queryPermission() method of the FileSystemHandle interface queries the current permission state of the current 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.

If PermissionStatus.state returns "prompt" the website will have to call requestPermission() before any operations on the handle can be done. If this returns "denied" any operations will reject. Usually handles returned by the local file system handle factories will initially return "granted" for their read permission state. However, other than through the user revoking permission, a handle retrieved from IndexedDB is also likely to return "prompt".



Thrown if mode is specified with a value other than 'read' or 'readwrite'


The following asynchronous function returns true if user has granted read or readwrite permissions to the file handle. Permission is requested if not.

// 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-querypermission

Browser compatibility

BCD tables only load in the browser

See also