not updating locale upon I18N.locale changed

[ghost]

date-picker-rails is running fine with my simple_form, however upon changing locale ( fr or en) , the calendar is still in english ..

I inserted into my application.js
//= require bootstrap-datepicker/core
//= require bootstrap-datepicker/locales/bootstrap-datepicker.fr
//= require bootstrap-datepicker/locales/bootstrap-datepicker.es

I have a simple_form input
class DatePickerInput < SimpleForm::Inputs::StringInput
def input
value = object.send(attribute_name) if object.respond_to? attribute_name
input_html_options[:value] ||= I18n.localize(value) if value.present?
input_html_classes << "datepicker"
super # leave StringInput do the real rendering
end
end

how the I18n.locale relate to the datepicker locale ?

[SOLVED]
I inserted into my layout application.html.haml
=javascript_tag "window.locale = #{I18n.locale.to_s.inspect};"

Then in my js file :
$(".datepicker").datepicker format: "dd-mm-yyyy", language: locale