JSFiddle - React, Tailwind, and code Playground

HTML

<p>Base Number: <span id="base">45.312</span></p>
<p>Using Math.round(): <span id="mathround"></span></p>
<p>Using Number.toFixed(): <span id="tofixed"></span></p>
<p>Using double not bitwise operator ~~: <span id="bitoperator"></span></p>

JavaScript

var base = Number(document.getElementById('base').innerHTML),
    mround = document.getElementById('mathround'),
    tofix = document.getElementById('tofixed'),
    doubleop = document.getElementById('bitoperator');

mround.innerHTML = Math.round(Number(base));
tofix.innerHTML = base.toFixed(0);
doubleop.innerHTML = ~~(base);