Applies dark theme to slack (OneDark)

darkSlack.sh

JS="
// First make sure the wrapper app is loaded
document.addEventListener('DOMContentLoaded', function() {
  // Then get its webviews
  let webviews = document.querySelectorAll('.TeamView webview');

  // Fetch our CSS in parallel ahead of time
  const cssPath =
    'https://raw.githubusercontent.com/Nockiro/slack-black-theme/master/custom.css';
  let cssPromise = fetch(cssPath).then((response) => response.text());

  let customCustomCSS = \`
   :root {
      /* Modify these to change your theme colors: */
      --primary: #61AFEF;
      --text: #ABB2BF;
      --background: #282C34;
      --background-elevated: #3B4048;
   }
   \`;

  // Insert a style tag into the wrapper view
  cssPromise.then((css) => {
    let s = document.createElement('style');
    s.type = 'text/css';
    s.innerHTML = css + customCustomCSS;
    document.head.appendChild(s);
  });

  // Wait for each webview to load
  webviews.forEach((webview) => {
    webview.addEventListener('ipc-message', (message) => {
      if (message.channel == 'didFinishLoading')
        // Finally add the CSS into the webview
        cssPromise.then((css) => {
          let script = \`
                     let s = document.createElement('style');
                     s.type = 'text/css';
                     s.id = 'slack-custom-css';
                     s.innerHTML = \\\`\${css + customCustomCSS}\\\`;
                     document.head.appendChild(s);
                     \`;
          webview.executeJavaScript(script);
        });
    });
  });
});"

SLACK_PATH='/Applications/Slack.app/Contents/Resources/app.asar.unpacked/src/static/'

echo "$JS" >> ${SLACK_PATH}ssb-interop.js

Need to run script as sudo to apply theme. Once run just restart slack.

Javascript comes from here with some fixes from #62