Why does datepicker highlight not work when I use "=="?

Question

   .Highlighted a{
   background-color : Green !important;
   background-image :none !important;
   color: White !important;
   font-weight:bold !important;
   font-size: 9pt;

}


  $(document).ready(function () {

                var date1 = new Date(2014, 5, 6);
                var date2 = new Date(2014, 5, 17);

                $('#datepicker').datepicker({

                   dateFormat: "mm/dd/yy",

                   beforeShowDay: function (date) {


                       if (date == date1 ) {

                            return [true, 'Highlighted', 'Available Date'];
                        }
                        return [false, '', ''];
                    }
                });
        });

This one doesn't work, because of date==date1. If I change it to date<=date1, it works fine. I thought javascript is a weakly typed language and it compares the content, rather than reference. I don't wanna do something like (date.getDay==date1.getDay &&....). Is there an easier way to compare the values?

possible duplicate of [Compare dates with JavaScript](http://stackoverflow.com/questions/492994/compare-dates-with-javascript) — Rodney G, Jun 20 '14 at 16:50

Shaunak D · Accepted Answer · 2014-06-20T17:01:54.247

5

Demo Fiddle

Use the + unary operator (reference) to convert the values to numerics for comparison.

The unary + operator converts its operand to Number type.

if (+date === +date1 ) {

      return [true, 'Highlighted', 'Available Date'];
}

OR

if (!(date - date1)) {

      return [true, 'Highlighted', 'Available Date'];
}

edited Jun 20 '14 at 17:01

answered Jun 20 '14 at 16:50

Shaunak D

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This essentially does what the other answer does, however I find the other answer easier to read. Plus, someone new to JavaScript wouldn't know what the heck is being done with the plusses. – j08691 Jun 20 '14 at 16:57
@j08691, i know, its just that I had solved the same problem using '+' some time before. – Shaunak D Jun 20 '14 at 16:58
1

@j08691 I'd argue that someone new to javascript isn't going to look at `getTime()` and know that it means _"seconds since 1970-01-01 UTC"_ rather than _"the time portion of a date"_. `valueOf()` seems more attractive... but still not great. – canon Jun 20 '14 at 17:13

score 3 · Answer 2 · edited May 23 '17 at 11:57

3

As suggested in this post you want to use the following to compare dates:

date.getTime() == date1.getTime()

edited May 23 '17 at 11:57

Community

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1

answered Jun 20 '14 at 16:48

ebo

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2

This has the same effect as `+date`, but is much easier to understand. – nullability Jun 20 '14 at 17:02

score 2 · Answer 3 · answered Jun 20 '14 at 17:01

2

Another way:

if (date.valueOf() == date1.valueOf())

answered Jun 20 '14 at 17:01

James

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Why does datepicker highlight not work when I use "=="?

3 Answers3

Demo Fiddle