JSFiddle - React, Tailwind, and code Playground

HTML

<body onload="data();">
        <select id="day">
            <option value="1">1</option>
            <option value="2">2</option>
            <option value="3">3</option>
            <option value="4">4</option>
            <option value="5">5</option>
            <option value="6">6</option>
            <option value="7">7</option>
            <option value="8">8</option>
            <option value="9">9</option>
            <option value="10">10</option>
            <option value="11">11</option>
            <option value="12">12</option>
            <option value="13">13</option>
            <option value="14">14</option>
            <option value="15">15</option>
            <option value="16">16</option>
            <option value="17">17</option>
            <option value="18">18</option>
            <option value="19">19</option>
            <option value="20">20</option>
        </select>
        <select id="month">
            <option value="Jan">Jan</option>
            <option value="Feb">Feb</option>
            <option value="Mar">Mar</option>
            <option value="Apr">Apr</option>
            <option value="May">May</option>
            <option value="Jun">Jun</option>
            <option value="Jul">Jul</option>
            <option value="Aug">Aug</option>
            <option value="Sep">Sep</option>
            <option value="Oct">Oct</option>
            <option value="Nov">Nov</option>
            <option value="Dec">Dec</option>
        </select>
        <select id="year">
            <option value="2014">2014</option>
            <option value="2015">2015</option>
        </select>
    </body>

JavaScript

function data() {
                var today = new Date();

                var month = new Array();
                month[0] = "January";
                month[1] = "February";
                month[2] = "March";
                month[3] = "April";
                month[4] = "May";
                month[5] = "June";
                month[6] = "July";
                month[7] = "August";
                month[8] = "September";
                month[9] = "October";
                month[10] = "November";
                month[11] = "December";
                
    
                var d = today.getDate();
                var m = month[today.getMonth()];
                var y = today.getFullYear();
                
     
     
     function getNextDate(currentMonth){
         switch(currentMonth) {
             case "January":
             case "March":
             case "May":
             case "July":
             case "August":
             case "October": if(d==31) {
                     d=1;
                     m=month[today.getMonth()+1];
                 } else {
                     d++;
                 }
                 break;
             case "December": if(d==31) {
                     d=1;
                     m=month[today.getMonth()+1];
                     y++;
                 } else {
                     d++;
                 }
                 break;
             case "February": if(d==28) {
                     d=1;
                     m=month[today.getMonth()+1];
             } else {
                     d++;
             }
                 break;
             default: if(d==30) {
                     d=1;
                     m=month[today.getMonth()+1];
             } else {
                     d++;
             }
                 break;
         }
     };
                getNextDate(m);
                document.getElementById('day').value = d;
                document.getElementById('month').value = m.slice(0,3);
               ...