[javascript] How display only years in input Bootstrap Datepicker?

I am using the following code to display only the years:

$("#datepicker").datepicker( {viewMode: "years", minViewMode: "years"});

but input appears in the format "dd/mm/yyyy"

How can I solve this since I do not have the format "yyyy"?

$("#year").datepicker( {
    format: "yyyy",
    viewMode: "years", 
    minViewMode: "years"
}).on('changeDate', function(e){
    $(this).datepicker('hide');
});

always year for bootstrap 3 datetimepicker https://eonasdan.github.io/bootstrap-datetimepicker/

   $('#year').datetimepicker({
        format: 'YYYY',
        viewMode: "years",
    });

    $("#year").on("dp.hide", function (e) {
        $('#year').datetimepicker('destroy');
        $('#year').datetimepicker({
            format: 'YYYY',
            viewMode: "years",
        });
    });

For bootstrap datetimepicker, assign decade value as follow:

$(".years").datetimepicker({
    format: "yyyy",
    startView: 'decade',
    minView: 'decade',
    viewSelect: 'decade',
    autoclose: true,
});

format: "YYYY" 

Should be capital instead of "yyyy"

For bootstrap 3 datepicker. (Note the capital letters)

$("#datetimepicker").datetimepicker( {
  format: "YYYY",
  viewMode: "years"
});