electron/docs/api/file-object.md

File Object

Use the HTML5 File API to work natively with files on the filesystem.

The DOM's File interface provides abstraction around native files in order to let users work on native files directly with the HTML5 file API. Electron has added a path attribute to the File interface which exposes the file's real path on filesystem.

Example on getting a real path from a dragged-onto-the-app file:

<div id="holder">
  Drag your file here
</div>

<script>
  const holder = document.getElementById('holder');
  holder.ondragover = () => {
    return false;
  };
  holder.ondragleave = holder.ondragend = () => {
    return false;
  };
  holder.ondrop = (e) => {
    e.preventDefault();
    const file = e.dataTransfer.files[0];
    console.log('File you dragged here is', file.path);
    return false;
  };
</script>