popup.js

var input, localData;
// wait for extension content to load
document.addEventListener('DOMContentLoaded', function(){

  input = document.querySelector('#input');
  // linux doesn't autofocus the input field
  input.focus();
// setup enter key listener
  input.addEventListener('keypress', function(e){
    if (e.keyCode === 13){
      console.log(input.value);
      save(input.value);
      input.value = '';
      window.close();
    }
  });

  // get existing data
  chrome.storage.sync.get(function(data){
    //console.log(data);
    if('items' in data)
      localData = data;
    else {
      data['items'] = [];
      localData = data;
    }
  });

  //register the open_edit_view command to trigger creation of a new tab
  chrome.commands.onCommand.addListener(function (command) {
    console.log(command);
  });

});

chrome.runtime.onMessage.addListener(function(message, sender, sendresponse){
  save(message);
  sendresponse();
});

function save(content) {
  var timestamp = new Date();
  var entry = {content:content, timestamp: String(timestamp), type:'note'};
  localData['items'].push(entry);
  chrome.storage.sync.set({'items':localData['items']});
}