Part of a tutorial on greenido.wordpress.com to show the power of Apps script as a simple site monitor

apps_script_site_monitor_1.js

function blogMonitor() { 
  var sheet  = SpreadsheetApp.getActiveSpreadsheet().getSheets()[2];
  var curUrl    = sheet.getRange("B1").getValue();  
  var curStatus = sheet.getRange("B3").getValue();  
  // monitorObj contain the url we are checking and its status (200 or 503 or any other HTML return code).
  var monitorObj = {url: curUrl, status: curStatus}; 
  
  // We will start as if the blog is down and hope for the best.
  var code = 503;
  try {    
    // Fetch the url of our site
    var response = UrlFetchApp.fetch(monitorObj.url);
    // Get the content (=HTML) in order to check for anchors 
    // that will validate the site is up and running
    var checkRes = response.getContentText();
  
    // You can put here any string that will let you know the site is up.
    if (checkRes.indexOf("ToDo - some string from the h1 or any other anchor on the site") < 1) {
      // The site doesn't render our validation string
      code = 503;
      Logger.log("Our site on: " + monitorObj.url + " is not OK");
    }
    else {
      // If it's something else let's get the HTML return code
      code = response.getResponseCode();    
      Logger.log("Our site on: " + monitorObj.url + " is OK. Code: "+ code);
    }
  } catch(error) {
    Logger.log("Err: during blogMonitor() we got: " + error);
  }
  
  // monitorObj contain two properties: site-url and its status.
  // The status will be the return code. E.g. 200 - we are good.
  monitorObj.status = checkAndNotify(monitorObj, code);    
  
  // store the obj in our meta data sheet or if you wish
  // you can use ScriptDB
  saveMonitorObj(monitorObj);
}