Check if client is not Phantom.Js et. al.

isNotPhantom.js

function isNotPhantomJs() {
    try {
        null[0]();
        return false
    } catch (e) {
        return !(typeof e.stack === 'undefined' || e.stack.toString().indexOf('phantomjs') != -1 || ('toString' in Math.sin && Math.sin.toString().indexOf('[native code') != -1 && document.getElementById.toString().indexOf('[native code') == -1) || window.callPhantom || /Phantom/.test(navigator.userAgent) || window.__phantomas || window.domAutomation || window.webdriver || document.documentElement.getAttribute('webdriver'))
    }
}