Where this date picker is included from?

Here http://pasteboard.co/cuSgKEdjS.png, you can see the date picker.
but
the code I used is very basic

<%= label_tag("To date") %> <%= date_field_tag 'tdate', '2015/08/01', class: 'form-control' %>

I didn’t worried about it until I tried to set default value and you can
see the default value ‘2015/08/01’ is not appearing in the date field.
It can’t be included from JQuery because I removed “//= require jquery”
and
“//= require jquery_ujs” from “application.js” and still its showing up.
Nothing special appears in Gemfile too.

ruby version: 2.2.4p230 (2015-12-16 revision 53155) [x86_64-linux]
Rails version: 4.2.6

I still don’t care if someone know how to force default value to show
up.

Thank you.

Depending on your browser, a normal HTML5 <input type="date"> (which
is what the ERB above creates) will generate a fancy picker, or it may
produce a thing that looks like a text field, but behaves differently
from one. Regardless how it appears, a “date” input will only accept
ISO-formatted dates as its value. Change your value= to ‘2015-08-01’ and
it may appear as you expect.

Walter

Change your value= to ‘2015-08-01’ and
it may appear as you expect.

Yeah you are right Walter. Its appearing now.

Thank you again.