<script src="https://cdn.jsdelivr.net/npm/mathjs@9.5.1/lib/browser/math.min.js"></script>
<p>看 console</p>

console.log("math", typeof math);

function calc(string) {
  return math.format(math.evaluate(string), { precision: 14 });
}
console.log(calc(".1+.2"));
console.log(calc(".28*100"));
console.log(calc("4.661*1855"));