send/frontend/src/download.js

const FileReceiver = require('./fileReceiver');
const $ = require('jquery');

$(document).ready(function() {
  $('#download-progress').hide();
  $('#send-file').click(() => {
    window.location.replace(`${window.location.origin}`);
  });
  const download = () => {
    const fileReceiver = new FileReceiver();
    const name = document.createElement('p');
    const $btn = $('#download-btn');

    fileReceiver.on('progress', percentComplete => {
      $('#download-page-one').hide();
      $('.send-new').hide();
      $('#download-progress').show();
      // update progress bar
      document.querySelector('#progress-bar').style.setProperty('--progress', percentComplete+'%');
      $('#progress-text').html(`${percentComplete}%`);
      //on complete
      if (percentComplete === 100) {
        fileReceiver.removeAllListeners('progress');
        $('#download-text').html('Download complete!');
        $('.send-new').show();
        $btn.text('Download complete!');
        $btn.attr('disabled', 'true');
      }
    });

    fileReceiver
    .download()
    .catch(() => {
      $('.title').text(
        'This link has expired or never existed in the first place.'
      );
      $('#download-btn').hide();
      $('#expired-img').show();
      console.log('The file has expired, or has already been deleted.');
      return;
    })
    .then(([decrypted, fname]) => {
      name.innerText = fname;
      const dataView = new DataView(decrypted);
      const blob = new Blob([dataView]);
      const downloadUrl = URL.createObjectURL(blob);

      const a = document.createElement('a');
      a.href = downloadUrl;
      if (window.navigator.msSaveBlob) {
        // if we are in microsoft edge or IE
        window.navigator.msSaveBlob(blob, fname);
        return;
      }
      a.download = fname;
      document.body.appendChild(a);
      a.click();
    });
  };

  window.download = download;
});