這次會整合先前介紹過的 xhr 、 alarms 、 notifications 三個特性,
做出一但有新的鐵人賽文章, 就會出現通知來提醒使用者.
manifest.json

{
   "manifest_version": 2,
   "name": "ironman6",
   "version": "1.0",
   "background": {
      "scripts": ["background.js"],
      "persistent": false
   },
   "permissions": [
      "alarms",
      "notifications",
      "http://ithelp.ithome.com.tw/*"
   ]
}

background.js

chrome.alarms.create('ironman6', {
    periodInMinutes : 1,
    when : Date.now()
});

chrome.alarms.onAlarm.addListener(getRSS);

function getRSS(alarm){
    var xhr = new XMLHttpRequest();
    var url = 'http://ithelp.ithome.com.tw/rss/question?tag=%E9%90%B5%E4%BA%BA%E8%B3%BD';
    xhr.open('GET', url);
    xhr.onload = function(e) {
        if (this.status === 200) {
            var xml  = this.responseXML;
            var time = xml.querySelector('lastBuildDate').textContent;
            if (time === localStorage['time']){return;}
            localStorage['time'] = time;
            var item = xml.querySelectorAll('item');
            var list = [];
            for (var i = 0; i < 5; i++){
                var rss   = item[i];
                var title = (i + 1) + ". " + rss.querySelector('title').textContent;
                var desc  = rss.querySelector('description').textContent;
                var link  = rss.querySelector('link').textContent;
                list.push({title: title, message: desc});
            }
            showList(list);
        }
    };
    xhr.send();
}

function showList(myItems){
    chrome.notifications.create(
        'Notifier' + Date.now(), {
            type: 'list',
            iconUrl: 'http://ithelp.ithome.com.tw/ironman6/img/ironman6_logo.png',
            title: '鐵人賽最新文章',
            message: 'Day 19',
            items: myItems
        },
        function(notificationId) {
            console.log(notificationId);
        }
    );
}