Convert Timezones in and out of System in a simple way!

moment-helper.js

//https://gist.github.com/NTICompass/9375143
/**
 * Gets Date based on PHP formats into Moment Format.
 * @param  {[type]} m [description]
 * @return {[type]}   [description]
 */
(function(m){
	/*
	 * PHP => moment.js
	 *
	 * http://www.php.net/manual/en/function.date.php
	 * http://momentjs.com/docs/#/displaying/format/
	 */
	var formatMap = {
		d: 'DD',
		D: 'ddd',
		j: 'D',
		l: 'dddd',
		N: 'E',
		S: function(){
			return '['+this.format('Do').replace(/\d*/g, '')+']';
		},
		w: 'd',
		z: function(){
			return this.format('DDD') - 1;
		},
		W: 'W',
		F: 'MMMM',
		m: 'MM',
		M: 'MMM',
		n: 'M',
		t: function(){
			return this.daysInMonth();
		},
		L: function(){
			return this.isLeapYear() ? 1 : 0;
		},
		o: 'GGGG',
		Y: 'YYYY',
		y: 'YY',
		a: 'a',
		A: 'A',
		B: function(){
			var thisUTC = this.clone().utc(),
				// Shamelessly stolen from http://javascript.about.com/library/blswatch.htm
				swatch = ((thisUTC.hours()+1) % 24) + (thisUTC.minutes() / 60) + (thisUTC.seconds() / 3600);
			return Math.floor(swatch * 1000 / 24);
		},
		g: 'h',
		G: 'H',
		h: 'hh',
		H: 'HH',
		i: 'mm',
		s: 'ss',
		u: '[u]', // not sure if moment has this
		e: '[e]', // moment does not have this
		I: function(){
			return this.isDST() ? 1 : 0;
		},
		O: 'ZZ',
		P: 'Z',
		T: '[T]', // deprecated in moment
		Z: function(){
			return parseInt(this.format('ZZ'), 10) * 36;
		},
		c: 'YYYY-MM-DD[T]HH:mm:ssZ',
		r: 'ddd, DD MMM YYYY HH:mm:ss ZZ',
		U: 'X'
	},
	formatEx = /[dDjlNSwzWFmMntLoYyaABgGhHisueIOPTZcrU]/g;

	m.fn.formatPHP = function(format){
		var that = this;
		
		return this.format(format.replace(formatEx, function(phpStr){
		  return typeof formatMap[phpStr] === 'function' ? formatMap[phpStr].call(that) : formatMap[phpStr];
		}));
	};
	m.convertPHPtoMoment = function(format){
		var that = this;
		
		return format.replace(formatEx, function(phpStr){
		  return typeof formatMap[phpStr] === 'function' ? formatMap[phpStr].call(that) : formatMap[phpStr];
		});
	};
}(moment));

/**
 * Set Formats of Dates in Moment from PHP. Set the format variables to your objects output in JS from PHP.
 * @param  {[type]} typeof moment        ! [description]
 * @return {[type]}        [description]
 */
var formats = {
  php: {
    date: 'Y-m-d',
    time: 'H:i:s',
    datetime: 'Y-m-d H:i:s'
};
  
if(typeof moment !== 'undefined'){
    formats.moment = {
        date: moment.convertPHPtoMoment(formats.php.date),
        time: moment.convertPHPtoMoment(formats.php.time),
        datetime: moment.convertPHPtoMoment(formats.php.datetime)
    };
} else {
	console.log(`Couldn't get moment formats since moment isn't loaded`);
}

timezone.php

<?php
/**
 * Missing from this file are the actual formats and user meta. You would need to write these for your system yourself.
 * Accepts PHP / MYQL Timezones. Best to use zones such as US/Eastern - US/Pacific, UTC, etc. 
 */
/**
 * Account Time and Date Formats.
 * @return [type] [description]
 */
function get_account_timezone(){
    return !empty(get_account_options()->formats->time_zone) ? get_account_options()->formats->time_zone : TIMEZONE;
}
function get_account_date_format(){
    return !empty(get_account_options()->formats->date) ? get_account_options()->formats->date : FORMAT_DATE;   
}
function get_account_time_format(){
    return !empty(get_account_options()->formats->time) ? get_account_options()->formats->time : FORMAT_TIME;   
}
function get_account_datetime_format(){
    return !empty(get_account_options()->formats->datetime) ? get_account_options()->formats->datetime : FORMAT_DATETIME;   
}
/**
 * User Timezone and Date Formats
 * @return [type] [description]
 */
function get_user_timezone(){
    return !empty(get_user_meta(get_account_id(), get_user_id(), 'format_timezone')) ? get_user_meta(get_account_id(), get_user_id(), 'format_timezone') : get_account_timezone();
}
function get_user_date_format(){
    return !empty(get_user_meta(get_account_id(), get_user_id(), 'format_date')) ? get_user_meta(get_account_id(), get_user_id(), 'format_date') : get_account_date_format();
}
function get_user_time_format(){
    return !empty(get_user_meta(get_account_id(), get_user_id(), 'format_time')) ? get_user_meta(get_account_id(), get_user_id(), 'format_time') : get_account_time_format();
}
function get_user_datetime_format(){
    return !empty(get_user_meta(get_account_id(), get_user_id(), 'format_datetime')) ? get_user_meta(get_account_id(), get_user_id(), 'format_datetime') : get_account_datetime_format();
}

/**
 * Current Local Dates and Times Formatted
 * @return [type] [description]
 */
function get_local_datetime(){
    return to_local_timezone(date('Y-m-d H:i:s'), 'datetime');
}
function get_local_date(){
    return to_local_timezone(date('Y-m-d H:i:s'), 'date');
}
function get_local_time(){
    return to_local_timezone(date('H:i:s'), 'time');
}

/** Current System Dates and Times Formatted
 * @return [type] [description]
 */
function get_system_datetime(){
    return to_system_timezone(date('Y-m-d H:i:s'), 'datetime');
}
function get_system_date(){
    return to_system_timezone(date('Y-m-d H:i:s'), 'date');
}
function get_system_time(){
    return to_system_timezone(date('H:i:s'), 'time');
}
/**
 * Formats date with no timezone conversion but checks user settings.
 * @param  [type] $date [description]
 * @return [type]       [description]
 */
function to_user_date_format($date){
    $date = new DateTime($date);
    return $date->format(get_user_date_format());
}

function to_user_time_format($date){
    $date = new DateTime($date);
    return $date->format(get_user_time_format());
}

function to_user_datetime_format($date){
    $date = new DateTime($date);
    return $date->format(get_user_datetime_format());
}
/**
 * Converts System Dates to Local Dates.
 * @param  [type] $date [description]
 * @param  string $type [description]
 * @return [type]       [description]
 */
function to_local_timezone($date, $type = 'datetime'){
    $system_timezone = new DateTimeZone(TIMEZONE);
    
    $date = new DateTime($date, $system_timezone);
    
    if(TIMEZONE !== get_user_timezone()){
        $user_timezone = new DateTimeZone(get_user_timezone());
        $date->setTimeZone($user_timezone);
    }

    if($type == 'datetime')  return $date->format(get_user_datetime_format());
        
    if($type == 'date')      return $date->format(get_user_date_format());
        
    if($type == 'time')      return $date->format(get_user_time_format());
    
    return $date->format(get_user_datetime_format());
}
/**
 * Converts Local Dates to System Dates. SYSTEM EXPECTS SERVER AND DATABASE TO BE SET TO SAME TIME ZONE!!!
 * @return [type] [description]
 */
function to_system_timezone($date, $type = ''){
    $system_timezone = new DateTimeZone(TIMEZONE);
    $user_timezone = new DateTimeZone(get_user_timezone());
    
    $date = new DateTime($date, $user_timezone);
    
    $date->setTimeZone($system_timezone);

    if($type == 'datetime')  return $date->format('Y-m-d H:i:s');
        
    if($type == 'date')      return $date->format('Y-m-d');
        
    if($type == 'time')      return $date->format('H:i:s');

    return $date->format('Y-m-d H:i:s');
}
/**
 * Converts Database Dates to Local Dates. SYSTEM EXPECTS SERVER AND DATABASE TO BE SET TO SAME TIME ZONE!!!
 * @return [type] [description]
 */
function to_local_timezone_sql($datetime, $name = ''){
    if(TIMEZONE !== get_user_timezone()){
        $system_timezone = strtoupper(TIMEZONE);
        $user_timezone = strtoupper(get_user_timezone());
        return "CONVERT_TZ( " . $datetime . ", '" . $system_timezone  . "', '" . $user_timezone . "' )" . ( !empty($name) ? " as '" . $name . "'" : '');
    }

    return $datetime . ( !empty($name) ? " as '" . $name . "'" : '');
}
/**
 * Converts Local Dates to System Database Dates. SYSTEM EXPECTS SERVER AND DATABASE TO BE SET TO SAME TIME ZONE!!!
 * @return [type] [description]
 */
function to_system_timezone_sql($datetime, $name = ''){
    if(TIMEZONE !== get_user_timezone()){
        $system_timezone = strtoupper(TIMEZONE);
        $user_timezone = strtoupper(get_user_timezone());
        return "CONVERT_TZ( " . $datetime . ", '" . $user_timezone . "', '" . $system_timezone . "' )" . ( !empty($name) ? " as '" . $name . "'" : '');
    }

    return $datetime . ( !empty($name) ? " as '" . $name . "'" : '');
}