JSFiddle - React, Tailwind, and code Playground

HTML

<a id="down" href="#" onclick="updateSpinner(this);">-</a><input id="content" value="0" type="text" style="width:30px" /><a id="up" href="#"  onclick="updateSpinner(this);">+</a>

CSS

a
{
    text-decoration: none;
}

JavaScript

function updateSpinner(obj)
{
    var contentObj = document.getElementById("content");
    var value = parseInt(contentObj.value);
    if(obj.id == "down") {
        if(value > 0){
        value--;
        }
    } else {
        value++;
    }
    contentObj.value = value;
}