Replicate PHP's native date() formatting in JavaScript for many common format types

dateFormat.js

/**
 * Return a formated string from a date Object mimicking PHP's date() functionality
 *
 * format  string  "Y-m-d H:i:s" or similar PHP-style date format string
 * date    mixed   Date Object, Datestring, or milliseconds 
 *
 */
function dateFormat(format,date){
	
	if(!date || date === "")
	{ 
		date = new Date();
	}
	else if(typeof('date') !== 'object')
	{
		date = new Date(date.replace(/-/g,"/")); // attempt to convert string to date object	
	}
	
	var string = '',
		mo = date.getMonth(),   // month (0-11)
		m1 = mo+1,			    // month (1-12)
		dow = date.getDay(),    // day of week (0-6)
		d = date.getDate(),     // day of the month (1-31)
		y = date.getFullYear(), // 1999 or 2003
		h = date.getHours(),    // hour (0-23)
		mi = date.getMinutes(), // minute (0-59)
		s = date.getSeconds();  // seconds (0-59)
	
	for (var i = 0, len = format.length; i < len; i++) {
		switch(format[i])
		{
			case 'j': // Day of the month without leading zeros  (1 to 31)
				string+= d;
				break;
			
			case 'd': // Day of the month, 2 digits with leading zeros (01 to 31)
				string+= (d < 10) ? "0"+d : d;
				break;
			
			case 'l': // (lowercase 'L') A full textual representation of the day of the week
				var days = Array("Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday");
				string+= days[dow];
				break;
				
			case 'w': // Numeric representation of the day of the week (0=Sunday,1=Monday,...6=Saturday)
				string+= dow;
				break;
				
			case 'D': // A textual representation of a day, three letters
				days = Array("Sun","Mon","Tue","Wed","Thr","Fri","Sat");
				string+= days[dow];
				break;	
			
			case 'm': // Numeric representation of a month, with leading zeros (01 to 12)
				string+= (m1 < 10) ? "0"+m1 : m1;
				break;	
		
			case 'n': // Numeric representation of a month, without leading zeros (1 to 12)
				string+= m1;
				break;
			
			case 'F': // A full textual representation of a month, such as January or March 
				var months = Array("January","February","March","April","May","June","July","August","September","October","November","December");
				string+= months[mo];
				break;
				
			case 'M': // A short textual representation of a month, three letters (Jan - Dec)
				months = Array("Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec");
				string+= months[mo];
				break;
					
			case 'Y': // A full numeric representation of a year, 4 digits (1999 OR 2003)	
				string+= y;
				break;
				
			case 'y': // A two digit representation of a year (99 OR 03)
				string+= y.toString().slice(-2);
				break;
				
			case 'H': // 24-hour format of an hour with leading zeros (00 to 23)
				string+= (h < 10) ? "0"+h : h;
				break;
			
			case 'g': // 12-hour format of an hour without leading zeros (1 to 12)
				var hour = (h===0) ? 12 : h;
				string+= (hour > 12) ? hour -12 : hour;
				break;
				
			case 'h': // 12-hour format of an hour with leading zeros (01 to 12)
				hour = (h===0) ? 12 : h;
				hour = ( hour > 12) ? hour -12 : hour;
				string+= (hour < 10) ? "0"+hour : hour;
				break;
			
			case 'a': // Lowercase Ante meridiem and Post meridiem (am or pm)
				string+= (h < 12) ? "am" : "pm";
				break;		
			
			case 'i': // Minutes with leading zeros (00 to 59)
				string+= (mi < 10) ? "0"+mi : mi;
				break;
			
			case 's': // Seconds, with leading zeros (00 to 59)
				string+= (s < 10) ? "0"+s : s;
				break;
				
			case 'c': // ISO 8601 date (eg: 2012-11-20T18:05:54.944Z)
				string+= date.toISOString();
				break;		
				
			default:
				string+= format[i];
		}
	}

	return string;
}

Awesome function. Much thanks 4 share it :)

I created a fork, featuring the following extras:

• Improved iteration
• Better formatting
• Rename function to date() to match name in PHP (does not override Date())
• escaped characters are ignored (e.g. date("\\h h") -> "h 11")

Todo:

• further code optimisation

Shouldn't line 4 be as follows?
else if(typeof(date) !== 'object')

Hi, I'm not up to writing a fork, but couldn't you make the first case as so:

case '\\': // '\\' is required for checking single back-slash
    i++;
    // console.log(format[i]);
    string+= format[i];
    break;

This supports (as does the original PHP function) "F j, Y \\a\\t g:i a"
Of course, in PHP you only need a single back-slash for a character, but I couldn't think of a way to avoid the double-back-slash adjustment.

I am thrilled to have found this.

Thank You! BTW

Since I know that I am going to use this very much...
And since I am going to maintain my own implementation thereof...
And since I use a few configurations over and over...
And since I would otherwise be traveling to the PHP Documentation over and over...
I've added the following block at the very top of the function:

    //<supported Aliases>
    let formatAlias = format.toLowerCase();
    formatAlias = formatAlias === 'ddt' ? 'default date time' : formatAlias;
    formatAlias = formatAlias === 'dd' ? 'default date' : formatAlias;
    formatAlias = formatAlias === 'dt' ? 'default time' : formatAlias;
    format = formatAlias === 'default date time' ? "F j, Y, g:i a" : format;
    format = formatAlias === 'default date' ? "F j, Y" : format;
    format = formatAlias === 'default time' ? "g:i a" : format;
    format = formatAlias === 'course catalog date' ? 'l F j, Y' : format;
    format = formatAlias === 'calendar time' ? ''h:ia'' : format;
    //</supported Aliases>

Of course, this is very extensible.
FWIW $0.02

I also created a fork of this gist (can be found here), where I touched these:

• Made the code more readable (you can minify if you like)
• Renamed the function to date() to match name in PHP
• Added a check for if the date(timestamp) parameter provided is a number

Do check it out :)

Great function thank you! although in line 14 there's a small mistake.
It must be:
else if(typeof(date) !== 'object')
Instead of:
else if(typeof('date') !== 'object')

I was trying to find suitable solution for me and I ended up with writing my own
https://gist.github.com/kubiqsk/c60207a3075104df7cc1822a95053ecd