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[PATCH 06/13] gitweb.js: Extract and improve datetime handling

From
Jakub Narebski <jnareb@gmail.com>
Date
Apr 28, 2011, 19:04 UTC
Message-ID
<1304017451-12283-7-git-send-email-jnareb@gmail.com>
In-Reply-To
<1304017451-12283-1-git-send-email-jnareb@gmail.com>

Move formatDateISOLocal(epoch, timezone) function (and also helper timezoneOffset(timezoneInfo) function it requires) from common-lib.js to datetime.js

Add new functions:
* localTimezoneOffset - to get browser timezone offset in seconds
* localTimezoneInfo   - to get browser timezone in '(+|-)HHMM' format
* formatTimezoneInfo - turn offset in hours and minutes into '(+|-)HHMM'
* parseRFC2822Date - to parse RFC-2822 dates that gitweb uses into epoch
* formatDateRFC2882 - like formatDateISOLocal, only RFC-2822 format

All those functions are meant to be used in future commit 'gitweb: javascript ability to adjust time based on timezone'

An alternative would be to use e.g. Datejs (http://www.datejs.com) library, or JavaScript framework that has date formatting (perhaps as a plugin).

While at it escape '-' in character class inside tzRe regexp, as recommended by JSLint (http://www.jslint.com).

Signed-off-by: Jakub Narebski <jnareb@gmail.com>
---
This patch is unchanged from first version of the series.

The major difference to approach taken in J.H. patch is noticing that while in older browsers Date constructor (Date.parse class method) does not like ISO-8601 format (W3CDTF variant used in microformats), all browsers should be able to parse RFC-822 / RFC-2822 date... which is what gitweb generates.

So instead of using deprecated (because of accessibility considerations) datetime-design-pattern microformat, or newer value-class-pattern (perhaps in value-title variant), simply parse RFC-2822 date that gitweb generated.

formatTimezoneInfo() from lib/datetime.js in this patch is roughly equivalent to formatTZ() function from date.js in original patch by J.H. The interface is a bit different, though; also formatTimezoneInfo uses Math.abs instead of Math.sqrt+Math.pow (?), and it uses padLeft function from lib/common-lib.js. The algorithm in formatTimezoneInfo was manually checked that it works for negative fractional browser timezones.

formatDateRFC2882() from lib/datetime.js in this patch is roughly equivalent to dateOutputTZ() function from date.js in original patch by J.H. formatDateRFC2882() handles only +/-HHMM numerical timezones; knowledge about "utc" and "local" timezone settings is left out of this function (but see localTimezoneInfo() function in this patch). formatDateRFC2882() explicitly uses padding (via padLeft()), something that J.H. patch missed but was supposedly[*] fixed in Kevin Cernekee patch:

  Re: [PATCH 1/1] gitweb: javascript ability to adjust time based on timezone
  http://thread.gmane.org/gmane.comp.version-control.git/169384/focus=169891
  http://cache.gmane.org//gmane/comp/version-control/git/169891-001.bin
[*] "Supposedly" only because I haven't bothered to check patch sent
    as base64-encoded application/octet-stream attachement.
NOTE: tzRe was left as a global variable, as it was originally.  Some
sources recommend avoiding global variables in JavaScript for
additional reason of performance.
 gitweb/Makefile                    |    1 +
 gitweb/static/js/lib/common-lib.js |   51 -----------
 gitweb/static/js/lib/datetime.js   |  161 ++++++++++++++++++++++++++++++++++++
 3 files changed, 162 insertions(+), 51 deletions(-)
 create mode 100644 gitweb/static/js/lib/datetime.js
diff --git a/gitweb/Makefile b/gitweb/Makefile
index 0baa9df..403265a 100644
--- a/gitweb/Makefile
+++ b/gitweb/Makefile
@@ -117,6 +117,7 @@ GITWEB_FILES += static/git-logo.png static/git-favicon.png
 # js/lib/common-lib.js should be always first, then js/lib/*.js,
 # then the rest of files; js/gitweb.js should be last (if it exists)
 GITWEB_JSLIB_FILES += static/js/lib/common-lib.js
+GITWEB_JSLIB_FILES += static/js/lib/datetime.js
 GITWEB_JSLIB_FILES += static/js/javascript-detection.js
 GITWEB_JSLIB_FILES += static/js/blame_incremental.js
 
diff --git a/gitweb/static/js/lib/common-lib.js b/gitweb/static/js/lib/common-lib.js
index c45454e..d6b0c0d 100644
--- a/gitweb/static/js/lib/common-lib.js
+++ b/gitweb/static/js/lib/common-lib.js
@@ -89,57 +89,6 @@ function createRequestObject() {
 
 
 /* ............................................................ */
-/* time and data */
-
-/**
- * used to extract hours and minutes from timezone info, e.g '-0900'
- * @constant
- */
-var tzRe = /^([+-])([0-9][0-9])([0-9][0-9])$/;
-
-/**
- * convert numeric timezone +/-ZZZZ to offset from UTC in seconds
- *
- * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
- * @returns {Number} offset from UTC in seconds for timezone
- *
- * @globals tzRe
- */
-function timezoneOffset(timezoneInfo) {
-	var match = tzRe.exec(timezoneInfo);
-	var tz_sign = (match[1] === '-' ? -1 : +1);
-	var tz_hour = parseInt(match[2],10);
-	var tz_min  = parseInt(match[3],10);
-
-	return tz_sign*(((tz_hour*60) + tz_min)*60);
-}
-
-/**
- * return date in local time formatted in iso-8601 like format
- * 'yyyy-mm-dd HH:MM:SS +/-ZZZZ' e.g. '2005-08-07 21:49:46 +0200'
- *
- * @param {Number} epoch: seconds since '00:00:00 1970-01-01 UTC'
- * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
- * @returns {String} date in local time in iso-8601 like format
- */
-function formatDateISOLocal(epoch, timezoneInfo) {
-	// date corrected by timezone
-	var localDate = new Date(1000 * (epoch +
-		timezoneOffset(timezoneInfo)));
-	var localDateStr = // e.g. '2005-08-07'
-		localDate.getUTCFullYear()                 + '-' +
-		padLeft(localDate.getUTCMonth()+1, 2, '0') + '-' +
-		padLeft(localDate.getUTCDate(),    2, '0');
-	var localTimeStr = // e.g. '21:49:46'
-		padLeft(localDate.getUTCHours(),   2, '0') + ':' +
-		padLeft(localDate.getUTCMinutes(), 2, '0') + ':' +
-		padLeft(localDate.getUTCSeconds(), 2, '0');
-
-	return localDateStr + ' ' + localTimeStr + ' ' + timezoneInfo;
-}
-
-
-/* ............................................................ */
 /* unquoting/unescaping filenames */
 
 /**#@+
diff --git a/gitweb/static/js/lib/datetime.js b/gitweb/static/js/lib/datetime.js
new file mode 100644
index 0000000..b3dcedb
--- /dev/null
+++ b/gitweb/static/js/lib/datetime.js
@@ -0,0 +1,161 @@
+// Copyright (C) 2007, Fredrik Kuivinen <frekui@gmail.com>
+//               2007, Petr Baudis <pasky@suse.cz>
+//          2008-2011, Jakub Narebski <jnareb@gmail.com>
+
+/**
+ * @fileOverview Datetime manipulation: parsing and formatting
+ * @license GPLv2 or later
+ */
+
+
+/* ............................................................ */
+/* parsing and retrieving datetime related information */
+
+/**
+ * used to extract hours and minutes from timezone info, e.g '-0900'
+ * @constant
+ */
+var tzRe = /^([+\-])([0-9][0-9])([0-9][0-9])$/;
+
+/**
+ * convert numeric timezone +/-ZZZZ to offset from UTC in seconds
+ *
+ * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
+ * @returns {Number} offset from UTC in seconds for timezone
+ *
+ * @globals tzRe
+ */
+function timezoneOffset(timezoneInfo) {
+	var match = tzRe.exec(timezoneInfo);
+	var tz_sign = (match[1] === '-' ? -1 : +1);
+	var tz_hour = parseInt(match[2],10);
+	var tz_min  = parseInt(match[3],10);
+
+	return tz_sign*(((tz_hour*60) + tz_min)*60);
+}
+
+/**
+ * return local (browser) timezone as offset from UTC in seconds
+ *
+ * @returns {Number} offset from UTC in seconds for local timezone
+ */
+function localTimezoneOffset() {
+	// getTimezoneOffset returns the time-zone offset from UTC,
+	// in _minutes_, for the current locale
+	return ((new Date()).getTimezoneOffset() * -60);
+}
+
+/**
+ * return local (browser) timezone as numeric timezone '(+|-)HHMM'
+ *
+ * @returns {String} locat timezone as -/+ZZZZ
+ */
+function localTimezoneInfo() {
+	var tzOffsetMinutes = (new Date()).getTimezoneOffset() * -1;
+
+	return formatTimezoneInfo(0, tzOffsetMinutes);
+}
+
+
+/**
+ * Parse RFC-2822 date into a Unix timestamp (into epoch)
+ *
+ * @param {String} date: date in RFC-2822 format, e.g. 'Thu, 21 Dec 2000 16:01:07 +0200'
+ * @returns {Number} epoch i.e. seconds since '00:00:00 1970-01-01 UTC'
+ */
+function parseRFC2822Date(date) {
+	// Date.parse accepts the IETF standard (RFC 1123 Section 5.2.14 and elsewhere)
+	// date syntax, which is defined in RFC 2822 (obsoletes RFC 822)
+	// and returns number of _milli_seconds since January 1, 1970, 00:00:00 UTC
+	return Date.parse(date) / 1000;
+}
+
+
+/* ............................................................ */
+/* formatting date */
+
+/**
+ * format timezone offset as numerical timezone '(+|-)HHMM' or '(+|-)HH:MM'
+ *
+ * @param {Number} hours:    offset in hours, e.g. 2 for '+0200'
+ * @param {Number} [minutes] offset in minutes, e.g. 30 for '-4030';
+ *                           it is split into hours if not 0 <= minutes < 60,
+ *                           for example 1200 would give '+0100';
+ *                           defaults to 0
+ * @param {String} [sep] separator between hours and minutes part,
+ *                       default is '', might be ':' for W3CDTF (rfc-3339)
+ * @returns {String} timezone in '(+|-)HHMM' or '(+|-)HH:MM' format
+ */
+function formatTimezoneInfo(hours, minutes, sep) {
+	minutes = minutes || 0; // to be able to use formatTimezoneInfo(hh)
+	sep = sep || ''; // default format is +/-ZZZZ
+
+	if (minutes < 0 || minutes > 59) {
+		hours = minutes > 0 ? Math.floor(minutes / 60) : Math.ceil(minutes / 60);
+		minutes = Math.abs(minutes - 60*hours); // sign of minutes is sign of hours
+		// NOTE: this works correctly because there is no UTC-00:30 timezone
+	}
+
+	var tzSign = hours >= 0 ? '+' : '-';
+	if (hours < 0) {
+		hours = -hours; // sign is stored in tzSign
+	}
+
+	return tzSign + padLeft(hours, 2, '0') + sep + padLeft(minutes, 2, '0');
+}
+
+/**
+ * return date in local time formatted in iso-8601 like format
+ * 'yyyy-mm-dd HH:MM:SS +/-ZZZZ' e.g. '2005-08-07 21:49:46 +0200'
+ *
+ * @param {Number} epoch: seconds since '00:00:00 1970-01-01 UTC'
+ * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
+ * @returns {String} date in local time in iso-8601 like format
+ */
+function formatDateISOLocal(epoch, timezoneInfo) {
+	// date corrected by timezone
+	var localDate = new Date(1000 * (epoch +
+		timezoneOffset(timezoneInfo)));
+	var localDateStr = // e.g. '2005-08-07'
+		localDate.getUTCFullYear()                 + '-' +
+		padLeft(localDate.getUTCMonth()+1, 2, '0') + '-' +
+		padLeft(localDate.getUTCDate(),    2, '0');
+	var localTimeStr = // e.g. '21:49:46'
+		padLeft(localDate.getUTCHours(),   2, '0') + ':' +
+		padLeft(localDate.getUTCMinutes(), 2, '0') + ':' +
+		padLeft(localDate.getUTCSeconds(), 2, '0');
+
+	return localDateStr + ' ' + localTimeStr + ' ' + timezoneInfo;
+}
+
+/**
+ * return date in local time formatted in rfc-2822 format
+ * e.g. 'Thu, 21 Dec 2000 16:01:07 +0200'
+ *
+ * @param {Number} epoch: seconds since '00:00:00 1970-01-01 UTC'
+ * @param {String} timezoneInfo: numeric timezone '(+|-)HHMM'
+ * @param {Boolean} [padDay] e.g. 'Sun, 07 Aug' if true, 'Sun, 7 Aug' otherwise
+ * @returns {String} date in local time in rfc-2822 format
+ */
+function formatDateRFC2882(epoch, timezoneInfo, padDay) {
+	// A short textual representation of a month, three letters
+	var months = ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
+	// A textual representation of a day, three letters
+	var days = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
+	// date corrected by timezone
+	var localDate = new Date(1000 * (epoch +
+		timezoneOffset(timezoneInfo)));
+	var localDateStr = // e.g. 'Sun, 7 Aug 2005' or 'Sun, 07 Aug 2005'
+		days[localDate.getUTCDay()] + ', ' +
+		(padDay ? padLeft(localDate.getUTCDate(),2,'0') : localDate.getUTCDate()) + ' ' +
+		months[localDate.getUTCMonth()] + ' ' +
+		localDate.getUTCFullYear();
+	var localTimeStr = // e.g. '21:49:46'
+		padLeft(localDate.getUTCHours(),   2, '0') + ':' +
+		padLeft(localDate.getUTCMinutes(), 2, '0') + ':' +
+		padLeft(localDate.getUTCSeconds(), 2, '0');
+
+	return localDateStr + ' ' + localTimeStr + ' ' + timezoneInfo;
+}
+
+/* end of datetime.js */

-- 
1.7.3
Previous: Jakub NarebskiNext: Jakub Narebski
Message 7 of 14 in “[PATCHv3 00/13] gitweb: Change timezone in dates using JavaScript”
  1. Jakub NarebskiApr 28, 2011
  2. 01/13 git-instaweb: Simplify build dependency on gitwebJakub Narebski, Apr 28, 2011
  3. 02/13 Remove gitweb/gitweb.cgi and other legacy targets from main MakefileJakub Narebski, Apr 28, 2011
  4. 03/13 gitweb: Split JavaScript for maintability, combining on buildJakub Narebski, Apr 28, 2011
  5. 04/13 gitweb.js: Update and improve comments in JavaScript filesJakub Narebski, Apr 28, 2011
  6. 05/13 gitweb.js: Provide default values for padding in padLeftStr and padLeftJakub Narebski, Apr 28, 2011
  7. 06/13 gitweb.js: Extract and improve datetime handlingJakub Narebski, Apr 28, 2011
  8. 07/13 gitweb.js: Introduce code to handle cookies from JavaScriptJakub Narebski, Apr 28, 2011
  9. 08/13 gitweb.js: Provide getElementsByClassName method (if it not exists)Jakub Narebski, Apr 28, 2011
  10. 09/13 gitweb: Refactor generating of long dates into format_timestamp_htmlJakub Narebski, Apr 28, 2011
  11. 10/13 gitweb: Unify the way long timestamp is displayedJakub Narebski, Apr 28, 2011
  12. 11/13 gitweb: JavaScript ability to adjust time based on timezoneJakub Narebski, Apr 28, 2011
  13. 12/13 gitweb.js: Add UI for selecting common timezone to display datesJakub Narebski, Apr 28, 2011
  14. 13/13 gitweb: Make JavaScript ability to adjust timezones configurableJakub Narebski, Apr 28, 2011

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