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FileSystemHandle: queryPermission() method

Secure context: This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

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.

Syntax

js

queryPermission(fileSystemHandlePermissionDescriptor)

Parameters

FileSystemHandlePermissionDescriptor Optional

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

  • 'mode': Can be either 'read' or 'readwrite'.

Return value

PermissionStatus.state which is one of 'granted', 'denied' or 'prompt'.

If this 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".

Exceptions

TypeError

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

Examples

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

js

// 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;
}

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
queryPermission 86 86 No No 72 No No 86 No 61 No 14.0

See also

© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/FileSystemHandle/queryPermission