Port of PHP's date() function to javascript

[mordred]

Okay, this an attempt to port PHP's date() function as much as possible to JavaScript. Could use some refactoring though. Any critique, comments, appraisal and any other opinion is very welcome. Feel free to discuss and also take a look at beetles code here: http://www.codingforums.com/showthread.php?s=&threadid=11069

Oh, and the date() function is described here: http://www.php.net/manual/en/function.date.php


Date.prototype.monthNames = new Array(
"January", "February", "March", "April",
"May", "June", "July", "August",
"September", "October", "November", "December"
);


Date.prototype.dayNames = new Array(
"Sunday", "Monday", "Tuesday", "Wednesday",
"Thursday", "Friday", "Saturday"
);


Date.prototype.format = function (formatStr) {
var heap = formatStr.split("");
var resHeap = new Array(heap.length);
var escapeChar = "\\"; // you can change this to something different, but
// don't use a character that has a formatting meaning,
// unless you want to disable it's functionality

// go through array and extract identifiers from its fields
for (var i = 0; i < heap.length; i++) {
switch(heap[i]) {
case escapeChar:
resHeap[i] = heap[i+1];
i++;
break;

case "a": // "am" or "pm"
var temp = this.getHours();
resHeap[i] = (temp < 12) ? "am" : "pm";
break;

case "A": // "AM" or "PM"
var temp = this.getHours();
resHeap[i] = (temp < 12) ? "AM" : "PM";
break;

case "d": // day of the month, 2 digits with leading zeros; i.e. "01" to "31"
var temp = String(this.getDate());
resHeap[i] = (temp.length > 1) ? temp : "0" + temp;
break;

case "D": // day of the week, textual, 3 letters; i.e. "Fri"
var temp = this.dayNames[this.getDay()];
resHeap[i] = temp.substring(0, 3);
break;

case "F": // month, textual, long; i.e. "January"
resHeap[i] = this.monthNames[this.getMonth()];
break;

case "g": // hour, 12-hour format without leading zeros; i.e. "1" to "12"
var temp = this.getHours();
resHeap[i] = (temp <= 12) ? temp : (temp - 12);
break;

case "G": // hour, 24-hour format without leading zeros; i.e. "0" to "23"
resHeap[i] = String(this.getHours());
break;

case "h": // hour, 12-hour format; i.e. "01" to "12"
var temp = String(this.getHours());
temp = (temp <= 12) ? temp : (temp - 12);
resHeap[i] = (temp.length > 1) ? temp : "0" + temp;
break;

case "H": // hour, 24-hour format; i.e. "00" to "23"
var temp = String(this.getHours());
resHeap[i] = (temp.length > 1) ? temp : "0" + temp;
break;

case "i": // minutes; i.e. "00" to "59"
var temp = String(this.getMinutes());
resHeap[i] = (temp.length > 1) ? temp : "0" + temp;
break;

case "I": // "1" if Daylight Savings Time, "0" otherwise. Works only on the northern hemisphere
var firstDay = new Date(this.getFullYear(), 0, 1);
resHeap[i] = (this.getTimezoneOffset() != firstDay.getTimezoneOffset()) ? (1) : (0);
break;

case "J": // day of the month without leading zeros; i.e. "1" to "31"
resHeap[i] = this.getDate();
break;

case "l": // day of the week, textual, long; i.e. "Friday"
resHeap[i] = this.dayNames[this.getDay()];
break;

case "L": // boolean for whether it is a leap year; i.e. "0" or "1"
resHeap[i] = (this.getFullYear() % 4) ? false : true;
break;

case "m": // month; i.e. "01" to "12"
var temp = String(this.getMonth() + 1);
resHeap[i] = (temp.length > 1) ? temp : "0" + temp;
break;

case "M": // month, textual, 3 letters; i.e. "Jan"
resHeap[i] = this.monthNames[this.getMonth()];
break;

case "n": // month without leading zeros; i.e. "1" to "12"
resHeap[i] = this.getMonth() + 1;
break;

case "O": // Difference to Greenwich time in hours; i.e. "+0200"
var minZone = this.getTimezoneOffset();
var mins = minZone % 60;
var hour = String(((minZone - mins) / 60) * -1);

if (hour.charAt(0) != "-") {
hour = "+" + hour;
}

hour = (hour.length == 3) ? (hour) : (hour.replace(/([+-])(\d)/, "$1" + 0 + "$2"));
resHeap[i] = hour + mins + "0";
break;

case "r": // RFC 822 formatted date; e.g. "Thu, 21 Dec 2000 16:01:07 +0200"
var dayName = this.dayNames[this.getDay()].substr(0, 3);
var monthName = this.monthNames[this.getMonth()].substr(0, 3);
resHeap[i] = dayName + ", " + this.getDate() + " " + monthName + this.format(" Y H:i:s O");
break;

case "s": // seconds; i.e. "00" to "59"
var temp = String(this.getSeconds());
resHeap[i] = (temp.length > 1) ? temp : "0" + temp;
break;

case "S": // English ordinal suffix for the day of the month, 2 characters; i.e. "st", "nd", "rd" or "th"
var temp = this.getDate();
var suffixes = ["st", "nd", "rd"];
var suffix = "";

if (temp >= 11 && temp <= 13) {
resHeap[i] = "th";
} else {
resHeap[i] = (suffix = suffixes[String(temp).substr(-1) - 1]) ? (suffix) : ("th");
}
break;


case "t": // number of days in the given month; i.e. "28" to "31"
resHeap[i] = this.getDay();
break;

/*
* T: Not implemented
*/

case "U": // seconds since the Unix Epoch (January 1 1970 00:00:00 GMT)
// remember that this does not return milisecs!
resHeap[i] = Math.floor(this.getTime() / 1000);
break;

case "w": // day of the week, numeric, i.e. "0" (Sunday) to "6" (Saturday)
resHeap[i] = this.getDay();
break;


case "W": // ISO-8601 week number of year, weeks starting on Monday
var startOfYear = new Date(this.getFullYear(), 0, 1, 0, 0, 0, 0);
var firstDay = startOfYear.getDay() - 1;

if (firstDay < 0) {
firstDay = 6;
}

var firstMonday = Date.UTC(this.getFullYear(), 0, 8 - firstDay);
var thisDay = Date.UTC(this.getFullYear(), this.getMonth(), this.getDate());
resHeap[i] = Math.floor((thisDay - firstMonday) / (1000 * 60 * 60 * 24 * 7)) + 2;
break;

case "y": // year, 2 digits; i.e. "99"
resHeap[i] = String(this.getFullYear()).substring(2);
break;

case "Y": // year, 4 digits; i.e. "1999"
resHeap[i] = this.getFullYear();
break;

case "z": // day of the year; i.e. "0" to "365"
var firstDay = Date.UTC(this.getFullYear(), 0, 0);
var thisDay = Date.UTC(this.getFullYear(), this.getMonth(), this.getDate());
resHeap[i] = Math.floor((thisDay - firstDay) / (1000 * 60 * 60 * 24));
break;

case "Z": // timezone offset in seconds (i.e. "-43200" to "43200").
resHeap[i] = this.getTimezoneOffset() * 60;
break;

default:
resHeap[i] = heap[i];
}
}

// return joined array
return resHeap.join("");
}

[mordred]

Argh, I had to exlude all comments and test cases from my script, 'cause it go too long. So here are some tests:


<html>
<head>
<title>date.format tests</title>
</head>
<body>
<h4>Javascript:</h4>
<!-- Include the format method in a separate file -->
<script type="text/javascript" src="date.format.js"></script>
<script type="text/javascript">
// test
var now = new Date();
document.write(now.format("d.m.Y") + "<br />");
document.write(now.format("\\T\\i\\m\\e \\i\\s h:m:s") + "<br />");
document.write(now.format("l dS of F Y h:i:s A") + "<br />");
document.write("Daylight Savings: " + now.format("I") + "<br />");
document.write("Week of year: " + now.format("W") + ", Day of year: " + now.format("z") + "<br />");
</script>
<br />
<br />
<h4>PHP:</h4>

<?php
// test
echo date("d.m.Y") . "<br />";
echo date("\\T\\i\\m\\e \\i\\s h:m:s") . "<br />";
echo date("l dS of F Y h:i:s A") . "<br />";
echo "Daylight Savings: " . date("I") . "<br />";
echo "Week of year: " . date("W") . ", Day of year: " . date("z");
?>
</body>
</html>

[joh6nn]

Mordred, i suggest that instead of this:

Date.prototype.monthNames = new Array(
"January", "February", "March", "April",
"May", "June", "July", "August",
"September", "October", "November", "December"
);

you just use Date.monthNames . there's a Global Date object, and doing it this way, would result in only one array, instead of an array for every Date object. unless, of course, you wanted every object to have it's own array.

[mordred]

Thanks for pointing that out. :)

I have to admit that it left me thinking for a while. My original intention really was to provide each instance of Date with a property monthNames. The idea behind was that you could have to date objects at the same time. That would enable the developer to overwrite each monthNames property with values he sees more fit for a specific date object, yet not interfering with another date object that should use the standard english names.

If I would implement monthNames like

Date.monthNames { // ...etc. }

then I'd have to call it as a class variable, like for formatting 'M':

case "M": // month, textual, 3 letters; i.e. "Jan"
resHeap[i] = Date.monthNames[this.getMonth()];
break;

which in return would lead to the situation that if you change the values of Date.monthNames, you change it for all instances.

Ok, I don't know how often it would be that you'd need to different monthNames implementation at one time, and I don't remember exactly why I eventually chose this approach.

Is there any different (dis)-advantageI just failed to see? Performance? Portability?