JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="startBidding" name="startBidding" value='12-15-2001 21:59:11'>
<input type="radio" name="expiry" value="5">  <span>  5 Days </span> 
<input type="radio" name="expiry" value="10"> <span> 10 Days </span>
<input type="text" id="endBidding" name="endBidding" >

JavaScript

$(document).ready(function() {
    $('input[type=radio][name=expiry]').change(function() {

        var days = this.value;
        var new_date = $("#startBidding").val().replace( /(\d{2})-(\d{2})-(\d{4}) /, "$3-$1-$2T");
        console.log(new_date);
        var startDate = new Date(new_date);
        console.log(startDate);
        startDate.setDate(startDate.getDate()+parseInt(days));
        var inputDate = (startDate.getMonth()+1)+'-'+(startDate.getDate())+'-'+(startDate.getFullYear());
        $("#endBidding").val(inputDate);
    });
});