code: function(src, el) {
  	        //todo: use jquery fallback if available for all QSA references
  	        var nodes = DOM.getNodeArray(el);
  	        nodes.forEach(function (node) {
  	            var img = DOM.newEl('img');
  	            var domProps = {};
  	            domProps[App.setup.dataAttr] = src;
  	            DOM.setAttr(img, domProps);
  	            node.appendChild(img);
  	        });
  	        return this;
  	    }
docs: Appends a placeholder to an element
  
  @param {string} src Placeholder URL string
  @param el A selector or a reference to a DOM node