Profile: bobA-2

Problem:
The user has a view datepicker filter that is not localized to the website language.

Solution:
The problem here is on WordPress: in v. 4.6 they decided to include the datepicker localization just in time when the datepicker script is enqueued. All works fine, as long as this datepicker script is loaded in the header.

In Views, we avoid loading scripts by default: we load them only when needed. That means that we include the datepicker script only if we have a date frontend filter. Unfortunately, that means that the script is enqueued in the footer, and the mechanism to load the localization automatically is not fired.

We have opened a new ticket for WordPress here https://core.trac.wordpress.org/ticket/50040

And we can force WordPress to localize the datepicker with the following code:

add_action( 'wp_print_footer_scripts', 'prefix_localize_jquery_ui_datepicker', 9 );
 
function prefix_localize_jquery_ui_datepicker() {
    if ( ! function_exists( 'wp_localize_jquery_ui_datepicker' ) ) {
        return;
    }
     
    wp_localize_jquery_ui_datepicker();
}

You can add this code in a new plugin, your (child)theme or in Toolset->Settings->Custom code.

Another workaround is to copy the localization(of datepicker) code inside the Javascript section of the view.