(Feature parity) Ignore null/undefined value for attributes

[saschanaz]

require("viperhtml")`<tag attr=${null} />`.toString()

hyperHTML removes attr while viperHTML emits attr="null".

[WebReflection]

the current optimizations over prefixed strings doesn't allow me to easily do that, so that passing null || '' might be a better work around.

I have written in the README the current status of this library:
https://github.com/WebReflection/viperHTML#warning

It's been a great first of a kind, but it would take a lot of effort to fully align it with hyperHTML at this point, which is way more successful and used than this project.

Apologies if this was not the kind of answer you were expecting, but I am also sure you moved somewhere else since June 2019.

Closing as won't fix, thanks for your understanding.