delay loading for react bundle

delaybundle.js

// defer loading of non-essential JS until DOM loaded event
function() {
  window.addEventListener("load", function() {
    var s, t;
    s = document.createElement("script");
    s.type = "text/javascript";
    s.src =
      "https://www.paypalobjects.com/digitalassets/c/website/marketing/global/kui/js/opinionLab-2.1.0.js";
    t = document.getElementsByTagName("body")[0];
    t.appendChild(s);
  });
});

// defer loading for the client side JS after DOM loaded event
// this is because we are doing SSR
function(){
    function loadScript(src, cb) {
      var s, r, t;
      r = false;
      s = document.createElement("script");
      s.type = "text/javascript";
      s.src = src;
      s.onload = s.onreadystatechange = function() {
        if (!r && (!this.readyState || this.readyState == "complete")) {
          r = true;
          cb();
        }
      };
      t = document.getElementsByTagName("body")[0];
      t.appendChild(s);
    }
    function mountCode() {
        if (typeof window !== "undefined" && window.document && window.document.createElement) {
            var appElement = React.createElement(window.PageBundle.default,   {modelData: window.modelData});
            ReactDOM.hydrate(appElement, window.document.getElementById("app-element-mountpoint"));
        }
    }
    window.addEventListener('load', function() {
        loadScript("https://www.paypalobjects.com/eboxapps/js/5f/7981d3071109ab488093d2ba7e4ca87ff7629e.js", mountCode);
    });
});