JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" id="calculator" />
<div id="result"></div>
JavaScript
var input = document.getElementById('calculator');
var result = document.getElementById('result');
input.addEventListener('keyup', calcular);
function calcular(){
//var conta = eval(this.value);
var conta = new Function("return " + this.value);
var resultado = conta();
result.innerHTML = resultado;
}