code: function getImageIndex(images) {
      var imageIndex = 0;
  
      if (images) {
        // this is NOT the first time this method is ran on this instance of jsPDF object.
        imageIndex = Object.keys ? Object.keys(images).length : function (o) {
          var i = 0;
  
          for (var e in o) {
            if (o.hasOwnProperty(e)) {
              i++;
            }
          }
  
          return i;
        }(images);
      }
  
      return imageIndex;
    }
docs: Image functionality ported from pdf.js