Are both index.html and index.js needed?
<p>I am learning about react, node.js in an application, I am doing in a group. The project has some restricted guidelines but my question is about whether index.html and index.js are needed together. </p>

<p>I have an index.html file already, but I want to create an index.js as well. 
Is this helpful or only one would be necessary? My group thinks I need it, I just don't understand why.</p>