Get document height

getDocumentPageHeight.js

/**
* Document sizes are a browser compatibility nightmare because, although all browsers expose clientHeight and s
* crollHeight properties, they don't all agree how the values are calculated.
* @return {float} Height of the page after calulation.
* */
function getDocumentHeight(){
  var body = document.body,
      html = document.documentElement;


  var height = Math.max( body.scrollHeight, body.offsetHeight, html.clientHeight, html.scrollHeight, html.offsetHeight );
  return height
}