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FileSystemDirectoryEntry: createReader() method

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

Syntax

js

createReader()

Parameters

None.

Return value

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

Examples

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

js

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

  let getEntries = () => {
    dirReader.readEntries(
      (results) => {
        if (results.length) {
          entries = entries.concat(toArray(results));
          getEntries();
        }
      },
      (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 been reached, and the recursion ends. Once control is returned to readDirectory(), the array is returned to the caller.

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
createReader 13 79 50 No No 11.1 ≤37 18 50 14 11.3 1.0

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/FileSystemDirectoryEntry/createReader