Keep selected files

htmx-files.js

var files;

htmx.defineExtension('file', {
  onEvent: function(type, evt) {
    if (type === 'htmx:beforeSwap') {
      files = htmx.findAll(evt.target, 'input[type="file"]');
    }
    if (type === 'htmx:afterSwap') {
      for (file of files) {
        const target = document.getElementsByClassName(file.className)[0];
        target.replaceWith(file);
      }
    }
  }
});