The showSaveFilePicker() method of the Window interface shows a file picker that allows a user to save a file. Either by selecting an existing file, or entering a name for a new file.

options Optional

An object containing options, which are as follows:

excludeAcceptAllOption Optional

A boolean value that defaults to false. By default, the picker should include an option to not apply any file type filters (instigated with the type option below). Setting this option to true means that option is not available.

id Optional

By specifying an ID, the browser can remember different directories for different IDs. If the same ID is used for another picker, the picker opens in the same directory.

startIn Optional

A FileSystemHandle or a well known directory ("desktop", "documents", "downloads", "music", "pictures", or "videos") to open the dialog in.

suggestedName Optional

A String. The suggested file name.

types Optional

An Array of allowed file types to save. Each item is an object with the following options:

description Optional

An optional description of the category of files types allowed. Default to be an empty string.

accept

An Object with the keys set to the MIME type and the values an Array of file extensions (see below for an example).

A Promise whose fulfillment handler receives a FileSystemFileHandle object.

AbortError DOMException

Thrown if the user dismisses the file picker without selecting or inputting a file, or if the user agent deems any selected files too sensitive or dangerous.

SecurityError DOMException

Thrown if the call was blocked by the same-origin policy or it was not called via a user interaction such as a button press.

Transient user activation is required. The user has to interact with the page or a UI element in order for this feature to work.

The following function shows a file picker, with text files highlighted for selection.

async function getNewFileHandle() {
  const opts = {
    types: [
      {
        description: "Text file",
        accept: { "text/plain": [".txt"] },
      },
    ],
  };
  return await window.showSaveFilePicker(opts);
}

• File System API
• The File System Access API: simplifying access to local files