uc.js for Firefox 77+

FindInPageByAltNum.uc.js

// https://gist.github.com/k-tsj/af03233fc023cb9e3280b0bce8c404b5
//
// License: Mozilla Public License 2.0
// Author: k-tsj

(() => {
  window.addEventListener("keydown", (aEvent) => {
    const keywords = BrowserSearch.searchBar.value.match(/"(?:\\"|\\\\|[^"])*"|\S+/g);
    function exec_find() {
      gFindBar._findField.value = keywords[aEvent.keyCode - KeyEvent.DOM_VK_1].replace(/^"|"$/g, "");
      gFindBar.onFindAgainCommand(aEvent.shiftKey);
      gFindBar.close();
    }

    if (aEvent.altKey && (KeyEvent.DOM_VK_1 <= aEvent.keyCode && aEvent.keyCode <= KeyEvent.DOM_VK_9)) {
      if (!gFindBar) {
        gLazyFindCommand("onFindCommand");
        setTimeout(exec_find, 100);
      } else {
        exec_find();
      }
    }
  }, false);
})();

SearchboxSync.uc.js

// https://gist.github.com/k-tsj/af03233fc023cb9e3280b0bce8c404b5
//
// License: Mozilla Public License 2.0
// Author: k-tsj

(() => {
  gBrowser.tabContainer.addEventListener("TabSelect", (event) => {
    setTimeout(() => {
        const url = new URL(event.target.linkedBrowser.currentURI.spec);
        const hostname = url.hostname;
        const q = url.searchParams.get("q");
        if ((hostname == "www.google.co.jp" || hostname == "www.google.com") && q) {
          BrowserSearch.searchBar.value = q;
        }
    }, (event.target.linkedBrowser.currentURI.spec == "about:blank") ? 500 : 0);
  } , 0);
})();

ShortcutSearch.uc.js

// https://gist.github.com/k-tsj/af03233fc023cb9e3280b0bce8c404b5
//
// License: Mozilla Public License 2.0
// Author: k-tsj

(() => {
  var engines;
  Services.search.getEngines().then(function (e) {
    engines = e;

    // set the first engine on startup.
    if (engines[0]) {
      Services.search.defaultEngine = engines[0];
    }
  });

  function setEngineByAlias(alias) {
    for (e of engines) {
      if (e._metaData.alias == alias) {
        Services.search.defaultEngine = e;
        setTimeout(() => {Services.search.defaultEngine = engines[0]}, 60 * 1000);
        return true;
      }
    }
    return false;
  }

  const searchbar = BrowserSearch.searchBar;
  searchbar.addEventListener("keydown", (aEvent) => {
    if (aEvent.keyCode == KeyEvent.DOM_VK_SPACE) {
      setTimeout(() => {
        const keywords = searchbar.value.split(/ /);
        if (setEngineByAlias(keywords[0])) {
            setTimeout(() => {searchbar.value = keywords.slice(1).join(' ');}, 50);
        }
      }, 50);
    }
  }, false);
})();