What is wrong with this simple HTML page that a date picker is not shown in FireFox 30.0 and IE 11?
Edge supports the datepicker, but after 4+ years, it looks like IE never will. Same with Safari desktop (though Safari mobile supports it). See: CanIUse datepicker support.
Chrome and Edge take the date format from the user's desktop system settings, which may be surprising if you're expecting ISO 8601 and your users don't live in Denmark or Canada.
JQuery's datepicker works with bootstrap 4 only if you use the REGULAR JQuery distribution. the Bootstrap 4 docs show the SLIM version, which tripped me up for a bit.
Other alternatives: