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FileSystemDirectoryEntry: createReader() method

files/en-us/web/api/filesystemdirectoryentry/createreader/index.md

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{{APIRef("File and Directory Entries API")}}

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

Syntax

js-nolint
createReader()

Parameters

None.

Return value

A {{domxref("FileSystemDirectoryReader")}} object which can be used to read the directory's entries.

Examples

This example creates an async function called readDirectory(), which fetches all of the entries in the specified {{domxref("FileSystemDirectoryEntry")}} and returns them in an array.

js
async function readDirectory(directory) {
  const dirReader = directory.createReader();
  const entries = [];

  while (true) {
    const results = await new Promise((resolve, reject) => {
      dirReader.readEntries(resolve, reject);
    });

    if (!results.length) {
      break;
    }

    for (const entry of results) {
      entries.push(entry);
    }
  }

  return entries;
}

This works by calling {{domxref("FileSystemDirectoryReader.readEntries", "readEntries()")}} repetitively to get all the entries in the directory, concatenating each batch to the array. When it returns an empty array, all entries have been read, and the loop ends.

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

  • File and Directory Entries API
  • {{domxref("FileSystemDirectoryReader")}}
  • {{domxref("FileSystemDirectoryEntry")}}
  • {{domxref("FileSystemFileEntry")}}
  • {{domxref("FileSystemEntry")}}