JSFiddle - React, Tailwind, and code Playground

HTML

<span class="num"><button>-</button><span>0</span><button>+</button></span>

CSS

.num button {display:inline-block;border-radius:6px;border:2px solid red;background:orange}
.num span{padding:1px 4px}

JavaScript

upDown = function({target,currentTarget}){
    switch(target.innerHTML){
      case "-" : currentTarget.childNodes[1].textContent--;break
      case "+" : currentTarget.childNodes[1].textContent++;  
    }
}
document.querySelectorAll('.num').forEach(function(y){
  y.addEventListener('click',upDown);
  y.addEventListener('touchend',upDown);
})