// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or vendor/assets/javascripts of plugins, if any, can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// the compiled file.
//
// WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED, ANY BLANK LINE SHOULD
// GO AFTER THE REQUIRES BELOW.
//
//= require jquery
//= require bootstrap-sprockets
//= require jquery_ujs
//= require nicEdit
//= require bootstrap-datepicker
//= require_tree .

$.fn.datepicker.defaults.format = "yyyy-mm-dd";

$(function() {
    $('.local-time').each(function(_) {
        var dd = new Date($(this).text());
        $(this).text(dd);
    });
})

// This is a manifest file that'll be compiled into application.js, which will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory, lib/assets/javascripts, vendor/assets/javascripts,
// or vendor/assets/javascripts of plugins, if any, can be referenced here using a relative path.
//
// It's not advisable to add code directly here, but if you do, it'll appear at the bottom of the
// the compiled file.
//
// WARNING: THE FIRST BLANK LINE MARKS THE END OF WHAT'S TO BE PROCESSED, ANY BLANK LINE SHOULD
// GO AFTER THE REQUIRES BELOW.
//
//= require jquery
//= require bootstrap-sprockets
//= require jquery_ujs
//= require nicEdit
//= require bootstrap-datepicker
//= require_tree .

$.fn.datepicker.defaults.format = "yyyy-mm-dd";

$(function() {
    $('.local-time').each(function(_) {
        var dd = new Date($(this).text());
        
        if (!isNaN(dd.getTime())) {
          $(this).text(dd);
        }
    });
})

Check for "invalid date" case in JS.