Fix feather *-off icons

// Fetch JSZip and FileSaver.js dependencies
Promise.all([
  'https://unpkg.com/jszip@3.1.4/dist/jszip.min.js',
  'https://unpkg.com/file-saver@1.3.3/FileSaver.min.js',
].map(src => new Promise((resolve, reject) => {
  const script = document.createElement('script');
  script.src = src;
  script.onload = resolve;
  script.onerror = reject;
  document.body.appendChild(script);
}))).then(() => {
  // Swap *-off line directions
  const oldLine = {x1: 1, y1: 1, x2: 23, y2: 23};
  const newLine = {x1: 23, y1: 1, x2: 1, y2: 23};
  const icons = Array.from(document.querySelectorAll('svg.feather'));
  icons
    .filter(icon => icon.getAttribute('class').includes('-off'))
    .map(icon => icon.querySelector('line'))
    .filter(line => Object.entries(oldLine)
      .reduce((acc, [attr, value]) => line.getAttribute(attr) == value), false)
    .map(line => Object.entries(newLine)
      .forEach(([attr, val]) => line.setAttribute(attr, val)));

  // Generate zip file
  const zip = new JSZip();
  icons.forEach(icon => zip.file(
    icon.getAttribute('class').replace('feather feather-', '') + '.svg',
    icon.outerHTML
  ));

  // Save zip file
  zip.generateAsync({type:'blob'})
    .then(content => saveAs(content, 'feather.zip'));
});