Pug is a popular view engine for express js.
Pug is a weird formatting of html, with everything just replacing the html syntax, without changing the structure of a html file. It will still have inputs, buttons <a></a> elements, a body, a head.
I have the pug syntax here. The reason to use pug would be to be able to easily add logic to html, in the same way your php can make html elements in a loop, pug can do that too.