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
Specification |
---|
File System Access # api-filesystemhandle-querypermission |
Browser compatibility
BCD tables only load in the browser