JSFiddle - React, Tailwind, and code Playground

HTML

<input id="foo" />

JavaScript

var foo = document.getElementById('foo');

foo.addEventListener('input', function (prev) {
    return function (evt) {
        if (!/^\d{0,6}(?:\.\d{0,2})?$/.test(this.value)) {
          this.value = prev;
        }
        else {
          prev = this.value;
        }
    };
}(foo.value), false);