text: 
  /*
  If the user clicks on an element which has the class "ua-choice":
  * fetch the element's textContent: for example, "IE 11"
  * pass it into the background page's setUaString() function
  */
  document.addEventListener("click", (e) => {
    if (!e.target.classList.contains("ua-choice")) {
      return;
    }
  
    var chosenUa = e.target.textContent;
    var backgroundPage = browser.extension.getBackgroundPage();
    backgroundPage.setUaString(chosenUa);
  });
  