popup.js

document.querySelector('#sort-containers-link').addEventListener('click', ()=> {
  const sortedTabsArray = [];
  browser.contextualIdentities.query({}).then(identities=> {
    identities.unshift({cookieStoreId: 'firefox-default'});
    console.log('identities: ', identities);

    const tabsArray = browser.tabs.query({}).then(tabsArray);

    identities.forEach(identity=> {
      tabsArray.forEach(tab=> {
        if (tab.cookieStoreId === identity.cookieStoreId) {
          sortedTabsArray.push(tab.id);
        }
      });
    });
  });
});