astro-google-fonts-optimizer/font-utils.ts

An Astro integration to optimize the Google Fonts loading performance

const userAgents: { name: string; ua: string }[] = [
  // this must always be the first element here!
  {
    name: 'woff',
    ua: 'Mozilla/5.0 (Windows NT 10.0; Trident/7.0; rv:11.0) like Gecko',
  },
  // from: https://github.com/fontsource/google-font-metadata/blob/main/data/user-agents.json
  {
    name: 'woff2',
    ua: 'Mozilla/5.0 (Windows NT 6.3; rv:39.0) Gecko/20100101 Firefox/44.0"',
  },
];

export function downloadFontCSS(url: string): Promise<string> {
  const fontDownloads = Promise.all(
    userAgents.map((entry) => {
      return fetch(url, { headers: { 'User-Agent': entry.ua } })
        .then((res) => res.text())
        .then((t) =>
          t.replace(/  +/g, '').replace(/\t+/g, '').replace(/\n+/g, '')
        );
    })
  );
  return fontDownloads.then((contents) => contents.join(' '));
}