Disclaimer: I've only run through the code once and may've misunderstood parts.

Typical usage:

// Via icons factory
icons.spinner().toHtmlString();
// Or directly
new Icon( .. ).toHtmlString();

• Constructor (View#initialize)
  • The Icon class in MobileFrontend JavaScript extends the mobile.startup/View class.
  • Given that Icon has a Hogan template set, View#initialize takes the if template path where possible and precompiles the template for later use.
  • The Icon class still has a tagName configured (not sure why, since it uses a template) and View creates an empty DOM element to be never used.
  • Further down the constructor it calls View#render(). I'd expect a consumer to have to all render() or indirectly by another method, not in the constructor already.
• Render (View#render)
  • Icon has a template and isTemplateMode, so render():
  • Calls Hogan to produce an HTML string.
  • Discards the previously created DOM element.
  • Implicitly parses the HTML into a new DOM element with jQuery.
• Embed (Icon#toHtmlString)
  • Creates another DOM element.
  • Appends the rendered node.
  • Calls on jQuery to let the browser serialise the node back to an HTML serialised string.
  • Embed the string in a larger HTML template, or call on jQuery to let the browser parse the HTML back into (another) DOM node.

This all seems quite wasteful.