JSFiddle - React, Tailwind, and code Playground

HTML

<span id=up_down>&#x25bc;</span>

JavaScript

var e = document.getElementById("up_down");
if ( escape(e.innerHTML) == '%u25B2' )
{
  e.innerHTML = '&#x25bc;';
}
else if ( escape(e.innerHTML) == '%u25BC' )
{
  e.innerHTML = '&#x25b2;';
} else alert(escape(e.innerHTML));