bookmarklet.min.js

javascript:(()=>{"function"==typeof window.__themeListenerUnsubscribe&&(window.__themeListenerUnsubscribe(),window.__themeListenerUnsubscribe=void 0);const e=window.matchMedia("(prefers-color-scheme: dark)"),t=async e=>{/255/.test(getComputedStyle(document.querySelector("#gbwa path")).getPropertyValue("color"))!==e.matches&&(async e=>{const t=e=>new Promise((t=>setTimeout(t,e)));var c=`[bgid="basic${e}"]:not(.a7J)`,o='[aria-label="Theme"] + button',n=document.querySelector(c),r=!n;if(!n){var i=document.querySelector(o);i||(document.querySelector('[data-tooltip="Settings"]').click(),await t(10),i=document.querySelector(o)),i.click(),await t(250),n=document.querySelector(c)}n.click(),r&&(await t(50),document.querySelector('[data-tooltip="Save & close"]').click())})(e.matches?"black":"white")};e.addEventListener("change",t),window.__themeListenerUnsubscribe=()=>{e.removeEventListener("change",t)}})()

gmail dark theme auto switcher.js

// changegmailtheme.js
/* env browser */
/* global document */

(() => {

const changeTheme = async (theme) => {
  const wait = (ms) => new Promise((resolve) => setTimeout(resolve, ms));
  var themeOptionSelector = `[bgid="basic${theme}"]:not(.a7J)`;
  var themeButtonSelector = '[aria-label="Theme"] + button';
  var themeOption = document.querySelector(themeOptionSelector);
  var openDialog = !themeOption;
  if (!themeOption) {
    var themeButton = document.querySelector(themeButtonSelector);
    if (!themeButton) {
      document.querySelector('[data-tooltip="Settings"]').click();
      await wait(10);
      themeButton = document.querySelector(themeButtonSelector);
    }
    themeButton.click();
    await wait(250);
    themeOption = document.querySelector(themeOptionSelector);
  }
  themeOption.click();
  if (openDialog) {
    await wait(50);
    document.querySelector('[data-tooltip="Save & close"]').click();
  }
});

if (typeof window.__themeListenerUnsubscribe === 'function') {
  window.__themeListenerUnsubscribe();
  window.__themeListenerUnsubscribe = undefined;
}

const mediaQueryList = window.matchMedia("(prefers-color-scheme: dark)")
/** @param {MediaQueryListEvent} change */ 
const listener = async (change) => {
  const config = JSON.parse(await fsp.readFile(configFilename, 'utf8'));
  const isDarkActive = /255/.test(getComputedStyle(document.querySelector("#gbwa path")).getPropertyValue('color'));
  if (isDarkActive !== change.matches) {
    changeTheme(change.matches ? 'black' : 'white');
  }
}
})();