text: var title = "ZealBots-Indexer";
  var urlAddress = ["nature", "biomedcentral", "wiley"];
  var taburl;
  function protocolIsApplicable(url) {
    var array =  url.split('/')[2].split('.')[1];
    return urlAddress.includes(array);
  }
  function initializeBrowserAction(tab) {
    if (protocolIsApplicable(tab.url)) {
      taburl = tab.url;
      browser.pageAction.setIcon({tabId: tab.id, path: "logo.png"});
      browser.pageAction.setTitle({tabId: tab.id, title: title});
      browser.pageAction.show(tab.id);
    }
  }
  
  function initializer(tabs){
      
    for (let tab of tabs) {
      initializeBrowserAction(tab);
      }
  }
  
  var gettingAllTabs = browser.tabs.query({});
  gettingAllTabs.then(initializer);
  
  function handleUpdated(tabId, changeInfo, tabInfo) {
      initializeBrowserAction(tabInfo);
  }
  
  browser.tabs.onUpdated.addListener(handleUpdated);
  
  // sending to popup
  function handleMessage(request, sender, sendResponse){
  
    if(request.requesting == "url"){      
        sendResponse({response :taburl});
  
    }
  
  }
  browser.runtime.onMessage.addListener(handleMessage);