Edit in JSFiddle

////////////////* popup.js *///////////////

// onMessage sends back strinfied selected text that gets pasted onto the popup for review
function pasteAddress() {
  chrome.tabs.query({ active:true, windowId: chrome.windows.WINDOW_ID_CURRENT},
  function(tab) {
    chrome.tabs.sendMessage(tab[0].id, {method: "getAddress"},
    function(response){
      var text = document.getElementById('address');
      text.innerHTML = response.data;
    });
  });
}