JSFiddle - React, Tailwind, and code Playground

by TrueBlueAussie

HTML

<label>month</label>
<input type="text" id="month"></input>
<label>year</label>
<input type="text" id="year"></input>
<button id="calculateDays">calculate days</button>

JavaScript

function getDaysInMonth(m, y) { //TrueBlueAussie
        return m===2?y&3||!(y%25)&&y&15?28:29:30+(m+(m>>3)&1);
    }

    document.getElementById("calculateDays").onclick = function () {
        console.log(
        getDaysInMonth(
        document.getElementById("month").value,
        document.getElementById("year").value));
    }