background.js

var gurl;
var savedKey;

function checkExistence(url){
  setUrl(url);
  chrome.storage.local.get(null, function(saved) {
    for (var key in saved) {
      console.log(key + " : " + saved[key]);
      if (gurl == saved[key]) {
        savedKey = key;
        isSaved(true);
        return;
      }   
    }
    console.log("isNotSaved");
    isSaved(false);
  });
}

function setUrl(url) {
  gurl = url;
  return;
}

function isSaved(bool) {
  chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
    var tabId = tabs[0].id;
    while (chrome.pageAction.onClicked.hasListener(remove_url)) {
      console.log('removing remove listener');
      chrome.pageAction.onClicked.removeListener(remove_url);
    }
    while (chrome.pageAction.onClicked.hasListener(save_url)) {
      console.log('removing save listener');
      chrome.pageAction.onClicked.removeListener(save_url);
    }
    if (bool) {
      chrome.pageAction.show(tabId);
      chrome.pageAction.setIcon({tabId: tabId, path: 'icon.png'});
       
      chrome.pageAction.onClicked.addListener(remove_url);
      console.log('ready to remove');
      return;
    }
    else {
      chrome.pageAction.show(tabId);
      chrome.pageAction.setIcon({tabId: tabId, path: 'icon2.png'});
      chrome.pageAction.onClicked.addListener(save_url);
      console.log('ready to save');
      return;
    }
  });
}

chrome.runtime.onMessage.addListener(checkExistence);

function save_url(tab) {
  chrome.pageAction.onClicked.removeListener(save_url);
  var time = new Date().toJSON().toString(); 
  var item = {};
  var things = [];
  things.push(gurl);
  var regex = new RegExp('/wiki/([^\\s\"]+)');
  var match = regex.exec(gurl);
  var title = decodeURIComponent(match[1]);
  things.push(title);
  item[time] = things;
  console.log("i am being saved: " + gurl);
  chrome.storage.local.set(item);
  storeXMLDoc(title);  
  chrome.pageAction.setIcon({tabId: tab.id, path: 'icon.png'});
  return;
}

function remove_url(tab) {
  chrome.pageAction.onClicked.removeListener(remove_url);
  console.log("i am being removed: " + savedKey);
  chrome.storage.local.remove(savedKey);
  chrome.pageAction.setIcon({tabId: tab.id, path: 'icon2.png'});
  return;
}


var request = new XMLHttpRequest();

function storeXMLDoc(title) {
  console.log(title);
  var reqLink = 'http://es.wikipedia.org/w/api.php?format=json&action=query&titles=' + title + '&prop=revisions&rvprop=content';
  request.open("GET",reqLink,false);
  request.send(null);
  console.log(request.responseType);
  var json = JSON.parse(request.responseText);
  for (item in json['query']['pages']) {
    if (json['query']['pages'][item]['revisions']) {
      console.log(json['query']['pages'][item]['revisions']['0']['*']);
    }
  }
}