Hi Icollia
The code you put inside a Generic Javascript node, is handled as a string passed as parameter to node’s library (org\knime\js\base\node\viz\generic\knime-generic-view-v3.js) which in turn parses it at run-time with the eval function: this is the reason why you don’t see the javascript code in final HTML.
Moreover, each Javascript node has a dedicated iframe element in the resulting web page.