backbone view test if element has datepicker

Question

First off: sorry for the terrible topic name

I have a backbone view that has an onRender() method. What it does is initializing all selects with an select jquery plugin (chosen) and some input text fields with the jquery plugin bootstrap-datepicker (https://github.com/uxsolutions/bootstrap-datepicker).

here is the code (coffeescript)

  onRender: =>
    ### init chosen select picker ###
    $('.chosen-select', @el).chosen
      width: '100%'
    ### init datepickers ###
    $('.date', @el).datepicker()

Now I want to write specs for the view and I am stuck with testing if the datpickers and chosen-selects where initialized on the proper elements elements.

So I strart trying on the console:

it was easy for the chosen-selects:

/* lets build the view  */
v = new MyBackboneView();
v.render();
v.onRender();
/* now lets grab a select that I expect to be an chosen select now */
select = $(':input[name="user_id"]', v.el);
/* now I check for the chosen function on the element */
$(select).data('chosen'); /* => is not undefined, yay! */

So now I wanted to do the same for the datepicker stuff.

/* lets build the view  */
v = new MyBackboneView();
v.render();
v.onRender();
/* now lets grab a input text field that I expect to be a datepicker now */
input = $(':input[name="start_date"]', v.el);
/* now I check for the datepicker function on the element */
$(input).data('datepicker'); /* => is undefined :-( */

So I can't check for the datepicker this way. But here is what I don't understand.

If I load the page in the browser, and I do the same thing like above with the element rendered in the browser (not only oon the console) I see the wanted object when checking for

$(input).data('datepicker');

So basicly when view is shown in browser:

/* lets grab a input text field that I expect to be a datepicker now */
input = $(':input[name="start_date"]');
/* now I check for the datepicker function on the element */
$(input).data('datepicker'); /* => is defined :-O */

Can someone explain this to me? I can't see through this one. And furthermore. Is there a better way to check for the use of a datepicker on an element in the console (or in an unit test)?