JSFiddle - React, Tailwind, and code Playground

HTML

<a onClick="toggle(this)"><span>&#9658;</span></a>

CSS

a{
 cursor: pointer;   
}

JavaScript

function toggle(elm) {
  var a = elm.getElementsByTagName('span')[0];
   

  if (a.textContent == '&#9658')
  {
    a.innerHTML = '&#9650;';
  }
  else
  {
    a.innerHTML = '&#9658;';
  }
}