javascript: create HTMLElement from string

You can create some dummy outer element:

  var div = document.createElement('DIV');

and then:

  div.innerHTML = '<table class="list"><tr><td><a href="xxx">title</a></td></tr></table>'

and then extract it from childNodes:

  div.firstChild

innerHTML is a Microsoft extension, but one universally supported on all modern browsers.

Of course you can form a simple function which does what you want from these snippets.

You can also append an element using the parent's innerHTML property like this:

        this.parentEl.innerHTML += `
<a-sphere 
  class="a-sim-body"
  dynamic-body 
  position="1 1 1" 
  radius="1" 
  color="blue">
</a-sphere>`