DeviantArt comment timestamp parser + userscript

code.js

function parseCommentDate(el){
	var _months = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Nov','Dec'],
		_pad = function(n){return n<10?'0'+n:n},
		time = el.title.replace(/^.*\(at (\d{1,2}):(\d{1,2}):(\d{1,2}) ([AP]M)\)$/, function(_,h,m,s,ampm){
			if (ampm === 'PM'){
				h = parseInt(h,10)+12;
				if (h >= 24)
					h -= 24;
			}
			else if (ampm === 'AM' && h == 12) h = 0;
			return [_pad(h),_pad(m),_pad(s)].join(':');
		}),
		date = el.innerHTML.replace(/([A-Z][a-z]{2}) (\d{1,2}), (\d{4})/,function(_,m,d,y){
			return [y,_pad(_months.indexOf(m)+1),_pad(d)].join('-');
		});
	return new Date(date+' '+time).toISOString();
}

code.user.js

// ==UserScript==
// @name         Standard DA Timestamps
// @namespace    http://localhost/
// @version      1.0
// @description  Replaces non-standard DeviantArt comment timestamps with standard <time> tags
// @author       SeinopSys
// @include      *.deviantart.com*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    function parseCommentDate(el){
        var _months = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'],
            _pad = function(n){return n<10?'0'+n:n;},
            time = el.title.replace(/^.*(?:\(at|,) (\d{1,2}):(\d{1,2}):(\d{1,2}) ([AP]M)\)?$/, function(_,h,m,s,ampm){
                if (ampm === 'PM'){
                    h = parseInt(h,10)+12;
                    if (h >= 24)
                        h -= 24;
                }
                else if (ampm === 'AM' && h == 12) h = 0;
                return [_pad(h),_pad(m),_pad(s)].join(':');
            }),
            date = (/\(at /.test(el.title) ? el.innerHTML : el.title).replace(/.*([A-Z][a-z]{2}) (\d{1,2})(?:, (\d{4}))?.*/,function(_,m,d,y){
                return [y?y:new Date().getFullYear(),_pad(_months.indexOf(m)+1),_pad(d)].join('-');
            });
        return new Date(date+' '+time).toISOString();
    }

    var listener = function(){
        // Comments
        var time = document.querySelectorAll('.cc-time'), el, time_tag;
        if (time.length)
            for (var i=0,l=time.length; i<l; i++){
                el = time[i].querySelector('a[title]');
                time_tag = document.createElement('time');
                time_tag.setAttribute('datetime', parseCommentDate(el));
                time_tag.innerHTML = el.innerHTML;
                el.innerHTML = '';
                el.appendChild(time_tag);
            }

        // Image post date
        el = document.querySelector('.dev-metainfo-content dl dd span[title][ts]');
        if (el){
            time_tag = document.createElement('time');
            var datetime = new Date(parseInt(el.getAttribute('ts')+'000',10)).toISOString();
            time_tag.setAttribute('datetime', datetime);
            time_tag.setAttribute('title', el.getAttribute('title'));
            time_tag.innerHTML = el.innerHTML;
            el.parentNode.replaceChild(time_tag, el);

            var first_metainf_copy = document.querySelector('.dev-metainfo-content .dev-metainfo-copy-control'),
                time_copy = first_metainf_copy.cloneNode(true);
            time_copy.innerHTML = "<strong>Posted at (ISO)</strong><br><input class='embed-code' readonly value='"+datetime+"'>";
            time_copy.addEventListener('click',function(){
                console.log(this);
                this.select();
            }.bind(time_copy.querySelector('.embed-code')));
            first_metainf_copy.parentNode.insertBefore(time_copy, first_metainf_copy);
        }
    };
    listener();
    window.addEventListener('popstate', listener);
})();