screenshot.js

var system = require('system');
var url = system.args[1];
var filename = system.args[2];
var page = new WebPage();

page.viewportSize = {
  width: 1920,
  height: 1080
};

page.clipRect = {
  top: 0,
  left: 0,
  width: 1920,
  height: 1080
};

page.settings.userAgent = 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36';

page.open(url, function (status) {
  page.render(filename);
  phantom.exit();
});