Comparing two dates in JavaScript but not working as I expected

Question

I am comparing two date, one is the current date and the other is selected from the input date type. I want if the selected date is less than the current date return true, but it does not returning true;

    function check_start_date(obj){


          var value= obj.value;
          var curr_date= new Date();
          var selected_date= new Date(value);
          curr_date= trim_time(curr_date);
          if(selected_date < curr_date){
               alert("less");
               return true;
           }
          else{
              return  false;
              }


    }

What does curr_date= trim_time(curr_date); do with the value? — Pengtuzi
– Pengtuzi, Commented Sep 14, 2014 at 13:01
@soulcheck 09/02/2014 It alerts true, if i select 09/15/2014 it return false. but when i select 09/14/2014(current date ) it again alert less . — Arif H-Shigri
– Arif H-Shigri, Commented Sep 14, 2014 at 13:03
Dear @Pengtuzi function trim_time(obj){ obj.setFullYear(obj.getFullYear(),obj.getMonth(),obj.getDate()); obj.setHours(0); obj.setMinutes(0); obj.setSeconds(0); return obj; } — Arif H-Shigri
– Arif H-Shigri, Commented Sep 14, 2014 at 13:04

Jeff Ogata · Accepted Answer · 2014-09-14 13:31:26Z

2

Your trim_time function is not removing milliseconds, so the trimmed value curr_date will be slightly greater than selected_date, except when the current time falls exactly on the second (milliseconds is 0).

answered Sep 14, 2014 at 13:31

Jeff Ogata

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Arif H-Shigri · Accepted Answer · 2014-09-14 14:04:40Z

1

I Changed My trim_time(obj) function and it did work :)

 function trim_time(obj){
     var obj1= new Date(obj.getFullYear(),obj.getMonth(),obj.getDate(),0,0,0);
    return obj1;
    }

answered Sep 14, 2014 at 14:04

Arif H-Shigri

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lucusp · Accepted Answer · 2014-09-14 13:12:08Z

0

My solution would be to use the Number() function. Then compare the two resulting numbers.

var curr_date = Number(new Date());

...

var selected_date = Number(new Date(value));

...

Then compare etc. Not tested btw, just some thoughts.

MDN explanation: Number() Function

answered Sep 14, 2014 at 13:12

lucusp

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2 Comments

Matt Browne Over a year ago

You don't need to convert to numbers to be able to compare dates; operators like < > and == work fine on Date objects themselves. Also, if you did want raw numbers from the date objects for some reason, you could just use the getTime() function.

lucusp Over a year ago

I don't disagree with you :), just something I would try if I was having problems with comparing dates.

user2417483 · Accepted Answer · 2014-09-14 13:20:02Z

0

You need to convert the dates to numbers (for simple comparison). My solution would be:

function check_start_date( obj ) {
  var value = new Date( obj.value ) * 1; //--- convert to number
  var curr_date = new Date();
  curr_date = new Date( curr_date.getFullYear(), curr_date.getMonth(), curr_date.getDate()) * 1; //--- remove time from the date
  if( value < curr_ date ) {
    alert( 'less' );
    return true;
  } else {
    return false;
  }
}

answered Sep 14, 2014 at 13:20

user2417483

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