Check if date is in the past Javascript

Question

All, I\'m using the jQuery UI for the date picker. I\'m trying to check with javascript though that the date the user has entered is in the past. Here is my form code:

Answer 1

$('#datepicker').datepicker().change(evt => {
  var selectedDate = $('#datepicker').datepicker('getDate');
  var now = new Date();
  now.setHours(0,0,0,0);
  if (selectedDate < now) {
    console.log("Selected date is in the past");
  } else {
    console.log("Selected date is NOT in the past");
  }
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://code.jquery.com/ui/1.12.1/jquery-ui.min.js"></script>
<input type="text" id="datepicker" name="event_date" class="datepicker">

Answer 2

function isPrevDate() {
    alert("startDate is " + Startdate);
    if(Startdate.length != 0 && Startdate !='') {
        var start_date = Startdate.split('-');
        alert("Input date: "+ start_date);
        start_date=start_date[1]+"/"+start_date[2]+"/"+start_date[0];
        alert("start date arrray format " + start_date);
        var a = new Date(start_date);
        //alert("The date is a" +a);
        var today = new Date();
        var day = today.getDate();
        var mon = today.getMonth()+1;
        var year = today.getFullYear();
        today = (mon+"/"+day+"/"+year);
        //alert(today);
        var today = new Date(today);
        alert("Today: "+today.getTime());
        alert("a : "+a.getTime());
        if(today.getTime() > a.getTime() )
        {
            alert("Please select Start date in range");
            return false;
        } else {
            return true;
        }
    }
}

Answer 3

var datep = $('#datepicker').val();

if(Date.parse(datep)-Date.parse(new Date())<0)
{
   // do something
}

Answer 4

To make the answer more re-usable for things other than just the datepicker change function you can create a prototype to handle this for you.

// safety check to see if the prototype name is already defined
Function.prototype.method = function (name, func) {
    if (!this.prototype[name]) {
        this.prototype[name] = func;
        return this;
    }
};
Date.method('inPast', function () {
    return this < new Date($.now());// the $.now() requires jQuery
});

// including this prototype as using in example
Date.method('addDays', function (days) {
    var date = new Date(this);
    date.setDate(date.getDate() + (days));    
    return date;
});

If you dont like the safety check you can use the conventional way to define prototypes:

Date.prototype.inPast = function(){
    return this < new Date($.now());// the $.now() requires jQuery
}

Example Usage

var dt = new Date($.now());
var yesterday = dt.addDays(-1);
var tomorrow = dt.addDays(1);
console.log('Yesterday: ' + yesterday.inPast());
console.log('Tomorrow: ' + tomorrow.inPast());