Would’ve been 5 with better documentation

Works well – I use a similar thing on my HTML responsive sites (hand coded variety). One issue is the clumsy way to stop this plugin loading on desktop sites – it needs to be ‘hidden’ for this to work properly – someone else posted the CSS code here, but I’ll repeat it as it also names the div class you need to do any other customisations as well:

/* hides scroll-back-to-top plugin on larger screens */
@media only screen and (min-width:768px){
  .scroll-back-to-top-wrapper{
    display: none;
  }
}