JSFiddle - React, Tailwind, and code Playground

by Manu Vashishtha

HTML

<input type="date" id="start_date" placeholder="Start Date"/>
<input type="number" id="days" placeholder="Days"/>
<input type="date" id="end_date" placeholder="End Date" readonly/>

JavaScript

;(function($, window, document, undefined){
    $("#days").on("change", function(){
    debugger;
       var date = new Date($("#start_date").val()),
           days = parseInt($("#days").val(), 10);
        
        if(!isNaN(date.getTime())){
            date.setDate(date.getDate() + days);
            
            $("#end_date").val(date.toInputFormat());
        } else {
            alert("Invalid Date");  
        }
    });
    
    
    //From: http://stackoverflow.com/questions/3066586/get-string-in-yyyymmdd-format-from-js-date-object
  Date.prototype.toInputFormat = function() {
  var yyyy = this.getFullYear().toString();
  var mm = (this.getMonth()+1).toString(); // getMonth() is zero-based
       var dd  = this.getDate().toString();
       var  _t=(dd[1]?dd:"0"+dd[0])+'/'+(mm[1]?mm:"0"+mm[0])+'/'+yyyy
       alert(_t);
       
       return yyyy + "-" + (mm[1]?mm:"0"+mm[0]) + "-" + (dd[1]?dd:"0"+dd[0]); // padding
    };
})(jQuery, this, document);