From: https://groups.google.com/forum/?hl=en&fromgroups=#!topic/phantomjs/5dbknDiH0Qs

gistfile1.txt

fs = require('fs');

function scrape() {
  var url = "some local url with asset served";
  var date = new Date();
  var stamp = date.getTime();
  console.log("scraping url: " + url);

  //Screenshot 1 - Routes and Traffic Time Table
  var page = require('webpage').create();
  page.viewportSize = {width: 400, height: 600};
  page.zoomfactor=1.1;
  page.open(url, function() {
    window.setTimeout(function() {
      page.render("./DataV1_" + stamp + ".png", {format:"png", quality: 100000});
      page.close();
    }, 5000);
  });

  var page1 = require('webpage').create();
  page1.viewportSize = {width: 1920, height: 1080};
  page1.zoomfactor=1.1;
  page1.open(url, function() {
    window.setTimeout(function() {
      page1.render("./DataV2_" + stamp + ".png", {format:"png", quality: 100000});
      page1.close();
    }, 5000);
  });

  var page2 = require('webpage').create();
  page2.open(url, function (status) {
    if (status !== 'success') {
      console.log('Unable to access network');
    } else {
      var ua = page2.evaluate(function () {
        return document.getElementById('<>').innerText;
      });
      f=null;
      f=fs.open("./DataV3_" + stamp + ".txt", "w");
      f.write(ua);
      f.close();
    }
    page2.close();
  });

}

//scrape every 5 minutes
// setInterval(scrape, 5 * 60 * 1000);

//scrape every 20 seconds
setInterval(scrape, 20 * 1000);