How to format existing date using JavaScript/jQuery

Your code has a few issues:

• You have a syntax error, you're calling getMintutes()
• You appear to be attempting to show the minutes twice, so you can remove one of those calls
• getFullYear() fits your needs better than getYear()
• You should use - not / to delimit the date values.
• You can add AM or PM to the end of the string by checking if hours < 12
• Your timestamp string isn't valid. It should not contain 'AM' or 'PM' - hence why the code doesn't work in Firefox.

With that in mind, try this:

var formatDate = function(date) {
  return date.getDate() + "-" + date.getMonth() + "-" + date.getFullYear() + " " +  ('0' + date.getHours()).slice(-2) + ":" + ('0' + date.getMinutes()).slice(-2) + ":" + ('0' + date.getSeconds()).slice(-2) + ' ' + (date.getHours() < 12 ? 'AM' : 'PM');
}

var timestamp = "2016-12-16 07:58:30";
var date = new Date(timestamp);
document.getElementById('divID').innerHTML = formatDate(date);

<div id="divID"></div>

You could use a library to make the date formatting logic simpler, but it's rather wasteful to load an entirely library when a single line of code works fine.

The timestamp you are using will return an invalid date so you should remove the AM. Using moment.js you can do it like this:

var timestamp = "2016-12-16 07:58:30";
var formattedDate = moment(timestamp).format('DD-MM-YYYY h:mm:ss A');
console.log(formattedDate);

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.5.1/moment.min.js"></script>

you can use a library named moment.js http://momentjs.com/

var date = new Date();
moment(date).format('DD-MM-YYYY HH:mm:ss A')

jQuery dateFormat is a separate plugin. You need to load that explicitly using a <script> tag.

You can use JQuery UI Datepicker for getting the formatted date like the following.

let myDate = '2020-11-10';
$.datepicker.formatDate('dd-M-yy', new Date(myDate));

The above code will return 10-Nov-2020.

You can get the desired output using JQuery UI Datepicker Widget as shown below.

var timestamp="2016-12-16 07:58:30 AM ";
var desiredTimestamp = $.datepicker.formatDate('dd-mm-yy', new Date(timestamp.split(' ')[0])) + ' ' + timestamp.split(' ')[1] + ' ' + timestamp.split(' ')[2];