Convert base64 to File and add to input file

convert-to-file.js

const dataURLtoFile = (dataurl, filename) => {
  var arr = dataurl.split(','),
    mime = arr[0].match(/:(.*?);/)[1],
    bstr = atob(arr[1]),
    n = bstr.length,
    u8arr = new Uint8Array(n);

  while (n--) {
    u8arr[n] = bstr.charCodeAt(n);
  }

  return new File([u8arr], filename, { type: mime });
};

const convertClick = (base64url, fileName) => {
  var file = dataURLtoFile(base64url, fileName);
  let container = new DataTransfer();
  container.items.add(file);
  document.querySelector('#input-file').files = container.files;
  var newfile = document.querySelector('#mainImageInput').files[0];
};