FileSystemDirectoryEntry.createReader()

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

The FileSystemDirectoryEntry interface's method createReader() returns a FileSystemDirectoryReader object which can be used to read the entries in the directory.

Syntax

directoryReader = FileSystemDirectoryEntry.createReader();

Parameters

None.

Return value

A FileSystemDirectoryReader object which can be used to read the directory's entries.

Example

This example creates a method called readDirectory(), which fetches all of the entries in the specified FileSystemDirectoryEntry and returns them in an array.

function readDirectory(directory) {
  let dirReader = directory.createReader();
  let entries = [];

  let getEntries = function() {
    dirReader.readEntries(function(results) {
      if (results.length) {
        entries = entries.concat(toArray(results));
        getEntries();
      }
    }, function(error) {
      /* handle error -- error is a FileError object */
    });
  };

  getEntries();
  return entries;
}

This works by creating an internal function, getEntries(), which calls itself recursively to get all the entries in the directory, concatenating each batch to the array. Each iteration, readEntries() is called to get more entries. When it returns an empty array, the end of the directory has beenr reached, and the recursion ends. Once control is returned to readDirectory(), the array is returned to the caller.

Specifications

Specification Status Comment
File and Directory Entries API
The definition of 'createReader()' in that specification.
Draft Initial specification.

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
createReader
Experimental
Chrome Full support 13Edge Full support 79Firefox Full support 50IE No support NoOpera No support NoSafari Full support 11.1WebView Android Full support ≤37Chrome Android Full support 18Firefox Android Full support 50Opera Android No support NoSafari iOS Full support 11.3Samsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
Experimental. Expect behavior to change in the future.
Experimental. Expect behavior to change in the future.

See also