NPM Module to format html string

Question

In an frontend application I have a string of JS code which I want to present to the user.

Currently it is formatted

<div class="foo"><div><span>Bar</span></div></div>

I am looking for an npm module which can process this string so that it looks like:

<div class="foo">
   <div>
      <span>
          Bar
       </span>
    </div>
</div>

I have tested several HMTL prettifiers / beautifiers but none of them seem to do do the job of adding linebreaks where non existed before.

Does anyone have any recommendations?