Declarative-ish JavaScript API for creating DOM?

I noticed that ParentNode.append() returns undefined, but if it returned this, then it would be possible to write stuff like this:

          document.body.append(
            document.createElement('div').append(
              document.createElement('span').append(
                'hello'
              ),
              new MyElement().append(
                new MyOtherElement().append(
                  document.createElement( 'div' ).append(
                    document.createElement('select').append(
                      document.createElement('option').append('option1'),
                      document.createElement('option').append('option2'),
                      document.createElement('option').append('option3')
                    )
                  )
                )
              )
            )
          )

which is somewhat “declarative”. Does any native API exist like that? It would also be easy to map JSX to that.

I know we can create these APIs ourselves. Just wondering about native options.

Updated the title, because obviously HTML is a declarative API. I meant to ask about declarative JS API.

Does any native API exist like that?

nope, but people have been talking about that:

• http://lists.w3.org/Archives/Public/public-webapps/2011JulSep/thread.html#msg537
• http://lists.w3.org/Archives/Public/www-dom/2011JulSep/thread.html#msg210
• http://lists.w3.org/Archives/Public/www-dom/2011OctDec/thread.html#msg20
• https://github.com/whatwg/dom/issues/150

document.createElement could accept the arguments to append directly (as array).

Actually, why not just use JavaScript (html) Tagged Template Literals?

Because it seems like string-parsing overhead at runtime. Or not?

HTML and JavaScript parsing is already costly enough. Just look at the original post -^ It’s much more costly than the equivalent HTML.

Also, instantiating this in one go is more efficient. And Template Literals can easily be pre-compiled and re-used. The equivalent JavaScript code has to be re-executed. (Any one of the various symbols could have changed)

Apple proposed extending the <template> element to handle interpolation, which might be similar enough to what you’re looking for?

w3c/webcomponents: HTML Template Instantiation

@Androbin @Tigt Interesting replies, thanks!

I checked out Surplus recently, it looks really nice too: converts JSX to in-place updates, similar to hyperHTML or lit-html approaches, but faster without DOM diffing.

This might be close to what you are looking for:

Inspired by kotlin-like layout parameters.

Lit-html also comes to mind, with string literals.

I’ve been using Solid.js lately, and made lume/element on top of it. But I should try to stay on topic.

Seems that if .append() returned this (or even the child like appendChild), it would be more useful. I wonder what was the reasoning that led to returning undefined.

@Androbin I was curious, so I made a benchmark to compare a HTML string parsing against a monkey-patched append() that returns this:

https://jsbench.me/1zkecipaat/1

It turns out the HTML parsing is 34.5% slower on my machine, for this particular example.