developer/Samples/Bot/scripts/tzDetect.js

   1 /*
   2  * Original script by Josh Fraser (http://www.onlineaspect.com)
   3  * Continued by Jon Nylander, (jon at pageloom dot com)
   4  * According to both of us, you are absolutely free to do whatever
   5  * you want with this code.
   6  *
   7  * This code is  maintained at bitbucket.org as jsTimezoneDetect.
   8  */
   9
  10 var HEMISPHERE_SOUTH = 'SOUTH';
  11 var HEMISPHERE_NORTH = 'NORTH';
  12 var HEMISPHERE_UNKNOWN = 'N/A';
  13 var olson = {}
  14
  15 /**
  16  * The keys in this dictionary are comma separated as such:
  17  *
  18  * First the offset compared to UTC time in minutes.
  19  *
  20  * Then a flag which is 0 if the timezone does not take daylight savings into account and 1 if it does.
  21  *
  22  * Thirdly an optional 's' signifies that the timezone is in the southern hemisphere, only interesting for timezones with DST.
  23  *
  24  * The values of the dictionary are TimeZone objects.
  25  */
  26 olson.timezones = {
  27         '-720,0'   : new TimeZone('-12:00','Etc/GMT+12', false),
  28         '-660,0'   : new TimeZone('-11:00','Pacific/Pago_Pago', false),
  29         '-600,1'   : new TimeZone('-11:00','America/Adak',true),
  30         '-660,1,s' : new TimeZone('-11:00','Pacific/Apia', true),
  31         '-600,0'   : new TimeZone('-10:00','Pacific/Honolulu', false),
  32         '-570,0'   : new TimeZone('-10:30','Pacific/Marquesas',false),
  33         '-540,0'   : new TimeZone('-09:00','Pacific/Gambier',false),
  34         '-540,1'   : new TimeZone('-09:00','America/Anchorage', true),
  35         '-480,1'   : new TimeZone('-08:00','America/Los_Angeles', true),
  36         '-480,0'   : new TimeZone('-08:00','Pacific/Pitcairn',false),
  37         '-420,0'   : new TimeZone('-07:00','America/Phoenix', false),
  38         '-420,1'   : new TimeZone('-07:00','America/Denver', true),
  39         '-360,0'   : new TimeZone('-06:00','America/Guatemala', false),
  40         '-360,1'   : new TimeZone('-06:00','America/Chicago', true),
  41         '-360,1,s' : new TimeZone('-06:00','Pacific/Easter',true),
  42         '-300,0'   : new TimeZone('-05:00','America/Bogota', false),
  43         '-300,1'   : new TimeZone('-05:00','America/New_York', true),
  44         '-270,0'   : new TimeZone('-04:30','America/Caracas', false),
  45         '-240,1'   : new TimeZone('-04:00','America/Halifax', true),
  46         '-240,0'   : new TimeZone('-04:00','America/Santo_Domingo', false),
  47         '-240,1,s' : new TimeZone('-04:00','America/Asuncion', true),
  48         '-210,1'   : new TimeZone('-03:30','America/St_Johns', true),
  49         '-180,1'   : new TimeZone('-03:00','America/Godthab', true),
  50         '-180,0'   : new TimeZone('-03:00','America/Argentina/Buenos_Aires', false),
  51         '-180,1,s' : new TimeZone('-03:00','America/Montevideo', true),
  52         '-120,0'   : new TimeZone('-02:00','America/Noronha', false),
  53         '-120,1'   : new TimeZone('-02:00','Etc/GMT+2', true),
  54         '-60,1'    : new TimeZone('-01:00','Atlantic/Azores', true),
  55         '-60,0'    : new TimeZone('-01:00','Atlantic/Cape_Verde', false),
  56         '0,0'      : new TimeZone('00:00','Etc/UTC', false),
  57         '0,1'      : new TimeZone('00:00','Europe/London', true),
  58         '60,1'     : new TimeZone('+01:00','Europe/Berlin', true),
  59         '60,0'     : new TimeZone('+01:00','Africa/Lagos', false),
  60         '60,1,s'   : new TimeZone('+01:00','Africa/Windhoek',true),
  61         '120,1'    : new TimeZone('+02:00','Asia/Beirut', true),
  62         '120,0'    : new TimeZone('+02:00','Africa/Johannesburg', false),
  63         '180,1'    : new TimeZone('+03:00','Europe/Moscow', true),
  64         '180,0'    : new TimeZone('+03:00','Asia/Baghdad', false),
  65         '210,1'    : new TimeZone('+03:30','Asia/Tehran', true),
  66         '240,0'    : new TimeZone('+04:00','Asia/Dubai', false),
  67         '240,1'    : new TimeZone('+04:00','Asia/Yerevan', true),
  68         '270,0'    : new TimeZone('+04:30','Asia/Kabul', false),
  69         '300,1'    : new TimeZone('+05:00','Asia/Yekaterinburg', true),
  70         '300,0'    : new TimeZone('+05:00','Asia/Karachi', false),
  71         '330,0'    : new TimeZone('+05:30','Asia/Kolkata', false),
  72         '345,0'    : new TimeZone('+05:45','Asia/Kathmandu', false),
  73         '360,0'    : new TimeZone('+06:00','Asia/Dhaka', false),
  74         '360,1'    : new TimeZone('+06:00','Asia/Omsk', true),
  75         '390,0'    : new TimeZone('+06:30','Asia/Rangoon', false),
  76         '420,1'    : new TimeZone('+07:00','Asia/Krasnoyarsk', true),
  77         '420,0'    : new TimeZone('+07:00','Asia/Jakarta', false),
  78         '480,0'    : new TimeZone('+08:00','Asia/Shanghai', false),
  79         '480,1'    : new TimeZone('+08:00','Asia/Irkutsk', true),
  80         '525,0'    : new TimeZone('+08:45','Australia/Eucla', true),
  81         '525,1,s'  : new TimeZone('+08:45','Australia/Eucla', true),
  82         '540,1'    : new TimeZone('+09:00','Asia/Yakutsk', true),
  83         '540,0'    : new TimeZone('+09:00','Asia/Tokyo', false),
  84         '570,0'    : new TimeZone('+09:30','Australia/Darwin', false),
  85         '570,1,s'  : new TimeZone('+09:30','Australia/Adelaide', true),
  86         '600,0'    : new TimeZone('+10:00','Australia/Brisbane', false),
  87         '600,1'    : new TimeZone('+10:00','Asia/Vladivostok', true),
  88         '600,1,s'  : new TimeZone('+10:00','Australia/Sydney', true),
  89         '630,1,s'  : new TimeZone('+10:30','Australia/Lord_Howe', true),
  90         '660,1'    : new TimeZone('+11:00','Asia/Kamchatka', true),
  91         '660,0'    : new TimeZone('+11:00','Pacific/Noumea', false),
  92         '690,0'    : new TimeZone('+11:30','Pacific/Norfolk', false),
  93         '720,1,s'  : new TimeZone('+12:00','Pacific/Auckland', true),
  94         '720,0'    : new TimeZone('+12:00','Pacific/Tarawa', false),
  95         '765,1,s'  : new TimeZone('+12:45','Pacific/Chatham', true),
  96         '780,0'    : new TimeZone('+13:00','Pacific/Tongatapu', false),
  97         '840,0'    : new TimeZone('+14:00','Pacific/Kiritimati', false)
  98 }
  99
 100 /**
 101  * This object contains information on when daylight savings starts for
 102  * different timezones.
 103  *
 104  * The list is short for a reason. Often we do not have to be very specific
 105  * to single out the correct timezone. But when we do, this list comes in
 106  * handy.
 107  *
 108  * Each value is a date denoting when daylight savings starts for that timezone.
 109  */
 110 olson.dst_start_dates = {
 111         'America/Denver' : new Date(2011, 2, 13, 3, 0, 0, 0),
 112         'America/Mazatlan' : new Date(2011, 3, 3, 3, 0, 0, 0),
 113         'America/Chicago' : new Date(2011, 2, 13, 3, 0, 0, 0),
 114         'America/Mexico_City' : new Date(2011, 3, 3, 3, 0, 0, 0),
 115         'Atlantic/Stanley' : new Date(2011, 8, 4, 7, 0, 0, 0),
 116         'America/Asuncion' : new Date(2011, 9, 2, 3, 0, 0, 0),
 117         'America/Santiago' : new Date(2011, 9, 9, 3, 0, 0, 0),
 118         'America/Campo_Grande' : new Date(2011, 9, 16, 5, 0, 0, 0),
 119         'America/Montevideo' : new Date(2011, 9, 2, 3, 0, 0, 0),
 120         'America/Sao_Paulo' : new Date(2011, 9, 16, 5, 0, 0, 0),
 121         'America/Los_Angeles' : new Date(2011, 2, 13, 8, 0, 0, 0),
 122         'America/Santa_Isabel' : new Date(2011, 3, 5, 8, 0, 0, 0),
 123         'America/Havana' : new Date(2011, 2, 13, 2, 0, 0, 0),
 124         'America/New_York' : new Date(2011, 2, 13, 7, 0, 0, 0),
 125         'Asia/Gaza' : new Date(2011, 2, 26, 23, 0, 0, 0),
 126         'Asia/Beirut' : new Date(2011, 2, 27, 1, 0, 0, 0),
 127         'Europe/Minsk' : new Date(2011, 2, 27, 3, 0, 0, 0),
 128         'Europe/Istanbul' : new Date(2011, 2, 27, 7, 0, 0, 0),
 129         'Asia/Damascus' : new Date(2011, 3, 1, 2, 0, 0, 0),
 130         'Asia/Jerusalem' : new Date(2011, 3, 1, 6, 0, 0, 0),
 131         'Africa/Cairo' : new Date(2011, 3, 29, 4, 0, 0, 0),
 132         'Asia/Yerevan' : new Date(2011, 2, 27, 4, 0, 0, 0),
 133         'Asia/Baku'    : new Date(2011, 2, 27, 8, 0, 0, 0),
 134         'Pacific/Auckland' : new Date(2011, 8, 26, 7, 0, 0, 0),
 135         'Pacific/Fiji' : new Date(2010, 11, 29, 23, 0, 0, 0),
 136         'America/Halifax' : new Date(2011, 2, 13, 6, 0, 0, 0),
 137         'America/Goose_Bay' : new Date(2011, 2, 13, 2, 1, 0, 0),
 138         'America/Miquelon' : new Date(2011, 2, 13, 5, 0, 0, 0),
 139         'America/Godthab' : new Date(2011, 2, 27, 1, 0, 0, 0)
 140 }
 141
 142 /**
 143  * The keys in this object are timezones that we know may be ambiguous after
 144  * a preliminary scan through the olson_tz object.
 145  *
 146  * The array of timezones to compare must be in the order that daylight savings
 147  * starts for the regions.
 148  */
 149 olson.ambiguity_list = {
 150         'America/Denver' : ['America/Denver','America/Mazatlan'],
 151         'America/Chicago' : ['America/Chicago','America/Mexico_City'],
 152         'America/Asuncion' : ['Atlantic/Stanley', 'America/Asuncion', 'America/Santiago','America/Campo_Grande'],
 153         'America/Montevideo' : ['America/Montevideo', 'America/Sao_Paulo'],
 154         'Asia/Beirut' : ['Asia/Gaza','Asia/Beirut', 'Europe/Minsk', 'Europe/Istanbul', 'Asia/Damascus', 'Asia/Jerusalem','Africa/Cairo'],
 155         'Asia/Yerevan' : ['Asia/Yerevan', 'Asia/Baku'],
 156         'Pacific/Auckland' : ['Pacific/Auckland', 'Pacific/Fiji'],
 157         'America/Los_Angeles' : ['America/Los_Angeles', 'America/Santa_Isabel'],
 158         'America/New_York' : ['America/Havana','America/New_York'],
 159         'America/Halifax' : ['America/Goose_Bay','America/Halifax'],
 160         'America/Godthab' : ['America/Miquelon', 'America/Godthab']
 161 }
 162
 163
 164 /**
 165  * A simple object containing information of utc_offset, which olson timezone key to use,
 166  * and if the timezone cares about daylight savings or not.
 167  *
 168  * @constructor
 169  * @param {string} offset - for example '-11:00'
 170  * @param {string} olson_tz - the olson Identifier, such as "America/Denver"
 171  * @param {boolean} uses_dst - flag for whether the time zone somehow cares about daylight savings.
 172  */
 173 function TimeZone(offset, olson_tz, uses_dst) {
 174         this.utc_offset = offset;
 175         this.olson_tz = olson_tz;
 176         this.uses_dst = uses_dst;
 177 }
 178
 179 /**
 180  * Prints out the result.
 181  * But before it does that, it calls this.ambiguity_check.
 182  */
 183 TimeZone.prototype.display = function() {
 184         this.ambiguity_check();
 185         var response_text = '<b>UTC-offset</b>: ' + this.utc_offset + '<br/>';
 186         response_text += '<b>Zoneinfo key</b>: ' + this.olson_tz + '<br/>';
 187         response_text += '<b>Zone uses DST</b>: ' + (this.uses_dst ? 'yes' : 'no') + '<br/>';
 188
 189         return response_text;
 190 }
 191
 192 /**
 193  * Checks if a timezone has possible ambiguities. I.e timezones that are similar.
 194  *
 195  * If the preliminary scan determines that we're in America/Denver. We double check
 196  * here that we're really there and not in America/Mazatlan.
 197  *
 198  * This is done by checking known dates for when daylight savings start for different
 199  * timezones.
 200  */
 201 TimeZone.prototype.ambiguity_check = function() {
 202         var local_ambiguity_list = olson.ambiguity_list[this.olson_tz];
 203
 204         if (typeof(local_ambiguity_list) == 'undefined') {
 205                 return;
 206         }
 207
 208         var length = local_ambiguity_list.length;
 209
 210         for (var i = 0; i < length; i++) {
 211                 var tz = local_ambiguity_list[i]
 212
 213                 if (date_is_dst(olson.dst_start_dates[tz])) {
 214                         this.olson_tz = tz;
 215                         return;
 216                 }
 217         }
 218 }
 219
 220 /**
 221  * Checks whether a given date is in daylight savings time.
 222  *
 223  * If the date supplied is after june, we assume that we're checking
 224  * for southern hemisphere DST.
 225  *
 226  * @param {Date} date
 227  * @returns {boolean}
 228  */
 229 function date_is_dst(date) {
 230         var base_offset = ( (date.getMonth() > 5 ? get_june_offset() : get_january_offset()) )
 231
 232         var date_offset = get_date_offset(date);
 233
 234         return (base_offset - date_offset) != 0;
 235 }
 236
 237 /**
 238  * Gets the offset in minutes from UTC for a certain date.
 239  *
 240  * @param date
 241  * @returns {number}
 242  */
 243 function get_date_offset(date) {
 244         return -date.getTimezoneOffset();
 245 }
 246
 247 /**
 248  * This function does some basic calculations to create information about
 249  * the user's timezone.
 250  *
 251  * Returns a primitive object on the format
 252  * {'utc_offset' : -9, 'dst': 1, hemisphere' : 'north'}
 253  * where dst is 1 if the region uses daylight savings.
 254  *
 255  * @returns {Object}
 256  */
 257 function get_timezone_info() {
 258         var january_offset = get_january_offset();
 259
 260         var june_offset = get_june_offset();
 261
 262         var diff = january_offset - june_offset;
 263
 264         if (diff < 0) {
 265             return {'utc_offset' : january_offset,
 266                         'dst':  1,
 267                         'hemisphere' : HEMISPHERE_NORTH}
 268         }
 269         else if (diff > 0) {
 270         return {'utc_offset' : june_offset,
 271                         'dst' : 1,
 272                         'hemisphere' : HEMISPHERE_SOUTH}
 273         }
 274
 275     return {'utc_offset' : january_offset,
 276                 'dst': 0,
 277                 'hemisphere' : HEMISPHERE_UNKNOWN}
 278 }
 279
 280 function get_january_offset() {
 281         return get_date_offset(new Date(2011, 0, 1, 0, 0, 0, 0));
 282 }
 283
 284 function get_june_offset() {
 285         return get_date_offset(new Date(2011, 5, 1, 0, 0, 0, 0));
 286 }
 287
 288 /**
 289  * Uses get_timezone_info() to formulate a key to use in the olson.timezones dictionary.
 290  *
 291  * Returns a primitive object on the format:
 292  * {'timezone': TimeZone, 'key' : 'the key used to find the TimeZone object'}
 293  *
 294  * @returns Object
 295  */
 296 function determine_timezone() {
 297         var timezone_key_info = get_timezone_info();
 298
 299         var hemisphere_suffix = ''
 300
 301         if (timezone_key_info.hemisphere == HEMISPHERE_SOUTH) {
 302                 hemisphere_suffix = ',s';
 303         }
 304
 305         var tz_key = timezone_key_info.utc_offset + ',' + timezone_key_info.dst + hemisphere_suffix
 306
 307         return {'timezone' : olson.timezones[tz_key], 'key' : tz_key}
 308 }
 309