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1 /**
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2 * This script gives you the zone info key representing your device's time zone setting.
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3 *
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4 * @name jsTimezoneDetect
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5 * @version 1.0.5
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6 * @author Jon Nylander
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7 * @license MIT License - http://www.opensource.org/licenses/mit-license.php
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8 *
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9 * For usage and examples, visit:
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10 * http://pellepim.bitbucket.org/jstz/
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11 *
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12 * Copyright (c) Jon Nylander
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13 */
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14
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15 /*jslint undef: true */
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16 /*global console, exports*/
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17
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18 (function(root) {
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19 /**
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20 * Namespace to hold all the code for timezone detection.
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21 */
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22 var jstz = (function () {
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23 'use strict';
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24 var HEMISPHERE_SOUTH = 's',
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25
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26 /**
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27 * Gets the offset in minutes from UTC for a certain date.
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28 * @param {Date} date
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29 * @returns {Number}
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30 */
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31 get_date_offset = function (date) {
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32 var offset = -date.getTimezoneOffset();
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33 return (offset !== null ? offset : 0);
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34 },
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35
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36 get_date = function (year, month, date) {
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37 var d = new Date();
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38 if (year !== undefined) {
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39 d.setFullYear(year);
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40 }
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41 d.setMonth(month);
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42 d.setDate(date);
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43 return d;
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44 },
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45
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46 get_january_offset = function (year) {
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47 return get_date_offset(get_date(year, 0 ,2));
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48 },
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49
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50 get_june_offset = function (year) {
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51 return get_date_offset(get_date(year, 5, 2));
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52 },
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53
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54 /**
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55 * Private method.
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56 * Checks whether a given date is in daylight saving time.
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57 * If the date supplied is after august, we assume that we're checking
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58 * for southern hemisphere DST.
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59 * @param {Date} date
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60 * @returns {Boolean}
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61 */
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62 date_is_dst = function (date) {
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63 var is_southern = date.getMonth() > 7,
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64 base_offset = is_southern ? get_june_offset(date.getFullYear()) :
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65 get_january_offset(date.getFullYear()),
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66 date_offset = get_date_offset(date),
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67 is_west = base_offset < 0,
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68 dst_offset = base_offset - date_offset;
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69
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70 if (!is_west && !is_southern) {
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71 return dst_offset < 0;
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72 }
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73
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74 return dst_offset !== 0;
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75 },
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76
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77 /**
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78 * This function does some basic calculations to create information about
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79 * the user's timezone. It uses REFERENCE_YEAR as a solid year for which
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80 * the script has been tested rather than depend on the year set by the
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81 * client device.
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82 *
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83 * Returns a key that can be used to do lookups in jstz.olson.timezones.
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84 * eg: "720,1,2".
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85 *
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86 * @returns {String}
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87 */
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88
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89 lookup_key = function () {
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90 var january_offset = get_january_offset(),
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91 june_offset = get_june_offset(),
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92 diff = january_offset - june_offset;
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93
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94 if (diff < 0) {
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95 return january_offset + ",1";
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96 } else if (diff > 0) {
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97 return june_offset + ",1," + HEMISPHERE_SOUTH;
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98 }
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99
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100 return january_offset + ",0";
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101 },
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102
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103 /**
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104 * Uses get_timezone_info() to formulate a key to use in the olson.timezones dictionary.
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105 *
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106 * Returns a primitive object on the format:
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107 * {'timezone': TimeZone, 'key' : 'the key used to find the TimeZone object'}
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108 *
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109 * @returns Object
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110 */
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111 determine = function () {
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112 var key = lookup_key();
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113 return new jstz.TimeZone(jstz.olson.timezones[key]);
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114 },
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115
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116 /**
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117 * This object contains information on when daylight savings starts for
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118 * different timezones.
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119 *
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120 * The list is short for a reason. Often we do not have to be very specific
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121 * to single out the correct timezone. But when we do, this list comes in
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122 * handy.
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123 *
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124 * Each value is a date denoting when daylight savings starts for that timezone.
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125 */
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126 dst_start_for = function (tz_name) {
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127
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128 var ru_pre_dst_change = new Date(2010, 6, 15, 1, 0, 0, 0), // In 2010 Russia had DST, this allows us to detect Russia :)
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129 dst_starts = {
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130 'America/Denver': new Date(2011, 2, 13, 3, 0, 0, 0),
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131 'America/Mazatlan': new Date(2011, 3, 3, 3, 0, 0, 0),
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132 'America/Chicago': new Date(2011, 2, 13, 3, 0, 0, 0),
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133 'America/Mexico_City': new Date(2011, 3, 3, 3, 0, 0, 0),
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134 'America/Asuncion': new Date(2012, 9, 7, 3, 0, 0, 0),
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135 'America/Santiago': new Date(2012, 9, 3, 3, 0, 0, 0),
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136 'America/Campo_Grande': new Date(2012, 9, 21, 5, 0, 0, 0),
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137 'America/Montevideo': new Date(2011, 9, 2, 3, 0, 0, 0),
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138 'America/Sao_Paulo': new Date(2011, 9, 16, 5, 0, 0, 0),
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139 'America/Los_Angeles': new Date(2011, 2, 13, 8, 0, 0, 0),
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140 'America/Santa_Isabel': new Date(2011, 3, 5, 8, 0, 0, 0),
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141 'America/Havana': new Date(2012, 2, 10, 2, 0, 0, 0),
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142 'America/New_York': new Date(2012, 2, 10, 7, 0, 0, 0),
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143 'Europe/Helsinki': new Date(2013, 2, 31, 5, 0, 0, 0),
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144 'Pacific/Auckland': new Date(2011, 8, 26, 7, 0, 0, 0),
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145 'America/Halifax': new Date(2011, 2, 13, 6, 0, 0, 0),
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146 'America/Goose_Bay': new Date(2011, 2, 13, 2, 1, 0, 0),
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147 'America/Miquelon': new Date(2011, 2, 13, 5, 0, 0, 0),
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148 'America/Godthab': new Date(2011, 2, 27, 1, 0, 0, 0),
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149 'Europe/Moscow': ru_pre_dst_change,
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150 'Asia/Amman': new Date(2013, 2, 29, 1, 0, 0, 0),
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151 'Asia/Beirut': new Date(2013, 2, 31, 2, 0, 0, 0),
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152 'Asia/Damascus': new Date(2013, 3, 6, 2, 0, 0, 0),
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153 'Asia/Jerusalem': new Date(2013, 2, 29, 5, 0, 0, 0),
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154 'Asia/Yekaterinburg': ru_pre_dst_change,
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155 'Asia/Omsk': ru_pre_dst_change,
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156 'Asia/Krasnoyarsk': ru_pre_dst_change,
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157 'Asia/Irkutsk': ru_pre_dst_change,
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158 'Asia/Yakutsk': ru_pre_dst_change,
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159 'Asia/Vladivostok': ru_pre_dst_change,
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160 'Asia/Baku': new Date(2013, 2, 31, 4, 0, 0),
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161 'Asia/Yerevan': new Date(2013, 2, 31, 3, 0, 0),
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162 'Asia/Kamchatka': ru_pre_dst_change,
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163 'Asia/Gaza': new Date(2010, 2, 27, 4, 0, 0),
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164 'Africa/Cairo': new Date(2010, 4, 1, 3, 0, 0),
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165 'Europe/Minsk': ru_pre_dst_change,
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166 'Pacific/Apia': new Date(2010, 10, 1, 1, 0, 0, 0),
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167 'Pacific/Fiji': new Date(2010, 11, 1, 0, 0, 0),
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168 'Australia/Perth': new Date(2008, 10, 1, 1, 0, 0, 0)
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169 };
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170
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171 return dst_starts[tz_name];
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172 };
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173
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174 return {
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175 determine: determine,
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176 date_is_dst: date_is_dst,
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177 dst_start_for: dst_start_for
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178 };
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179 }());
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180
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181 /**
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182 * Simple object to perform ambiguity check and to return name of time zone.
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183 */
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184 jstz.TimeZone = function (tz_name) {
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185 'use strict';
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186 /**
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187 * The keys in this object are timezones that we know may be ambiguous after
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188 * a preliminary scan through the olson_tz object.
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189 *
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190 * The array of timezones to compare must be in the order that daylight savings
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191 * starts for the regions.
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192 */
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193 var AMBIGUITIES = {
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194 'America/Denver': ['America/Denver', 'America/Mazatlan'],
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195 'America/Chicago': ['America/Chicago', 'America/Mexico_City'],
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196 'America/Santiago': ['America/Santiago', 'America/Asuncion', 'America/Campo_Grande'],
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197 'America/Montevideo': ['America/Montevideo', 'America/Sao_Paulo'],
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198 'Asia/Beirut': ['Asia/Amman', 'Asia/Jerusalem', 'Asia/Beirut', 'Europe/Helsinki','Asia/Damascus'],
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199 'Pacific/Auckland': ['Pacific/Auckland', 'Pacific/Fiji'],
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200 'America/Los_Angeles': ['America/Los_Angeles', 'America/Santa_Isabel'],
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201 'America/New_York': ['America/Havana', 'America/New_York'],
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202 'America/Halifax': ['America/Goose_Bay', 'America/Halifax'],
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203 'America/Godthab': ['America/Miquelon', 'America/Godthab'],
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204 'Asia/Dubai': ['Europe/Moscow'],
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205 'Asia/Dhaka': ['Asia/Yekaterinburg'],
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206 'Asia/Jakarta': ['Asia/Omsk'],
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207 'Asia/Shanghai': ['Asia/Krasnoyarsk', 'Australia/Perth'],
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208 'Asia/Tokyo': ['Asia/Irkutsk'],
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209 'Australia/Brisbane': ['Asia/Yakutsk'],
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210 'Pacific/Noumea': ['Asia/Vladivostok'],
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211 'Pacific/Tarawa': ['Asia/Kamchatka', 'Pacific/Fiji'],
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212 'Pacific/Tongatapu': ['Pacific/Apia'],
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213 'Asia/Baghdad': ['Europe/Minsk'],
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214 'Asia/Baku': ['Asia/Yerevan','Asia/Baku'],
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215 'Africa/Johannesburg': ['Asia/Gaza', 'Africa/Cairo']
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216 },
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217
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218 timezone_name = tz_name,
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219
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220 /**
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221 * Checks if a timezone has possible ambiguities. I.e timezones that are similar.
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222 *
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223 * For example, if the preliminary scan determines that we're in America/Denver.
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224 * We double check here that we're really there and not in America/Mazatlan.
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225 *
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226 * This is done by checking known dates for when daylight savings start for different
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227 * timezones during 2010 and 2011.
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228 */
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229 ambiguity_check = function () {
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230 var ambiguity_list = AMBIGUITIES[timezone_name],
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231 length = ambiguity_list.length,
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232 i = 0,
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233 tz = ambiguity_list[0];
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234
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235 for (; i < length; i += 1) {
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236 tz = ambiguity_list[i];
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237
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238 if (jstz.date_is_dst(jstz.dst_start_for(tz))) {
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239 timezone_name = tz;
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240 return;
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241 }
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242 }
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243 },
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244
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245 /**
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246 * Checks if it is possible that the timezone is ambiguous.
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247 */
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248 is_ambiguous = function () {
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249 return typeof (AMBIGUITIES[timezone_name]) !== 'undefined';
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250 };
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251
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252 if (is_ambiguous()) {
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253 ambiguity_check();
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254 }
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255
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256 return {
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257 name: function () {
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258 return timezone_name;
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259 }
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260 };
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261 };
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262
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263 jstz.olson = {};
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264
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265 /*
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266 * The keys in this dictionary are comma separated as such:
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267 *
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268 * First the offset compared to UTC time in minutes.
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269 *
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270 * Then a flag which is 0 if the timezone does not take daylight savings into account and 1 if it
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271 * does.
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272 *
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273 * Thirdly an optional 's' signifies that the timezone is in the southern hemisphere,
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274 * only interesting for timezones with DST.
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275 *
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276 * The mapped arrays is used for constructing the jstz.TimeZone object from within
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277 * jstz.determine_timezone();
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278 */
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279 jstz.olson.timezones = {
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280 '-720,0' : 'Pacific/Majuro',
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281 '-660,0' : 'Pacific/Pago_Pago',
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282 '-600,1' : 'America/Adak',
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283 '-600,0' : 'Pacific/Honolulu',
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284 '-570,0' : 'Pacific/Marquesas',
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285 '-540,0' : 'Pacific/Gambier',
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286 '-540,1' : 'America/Anchorage',
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287 '-480,1' : 'America/Los_Angeles',
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288 '-480,0' : 'Pacific/Pitcairn',
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289 '-420,0' : 'America/Phoenix',
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290 '-420,1' : 'America/Denver',
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291 '-360,0' : 'America/Guatemala',
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292 '-360,1' : 'America/Chicago',
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293 '-360,1,s' : 'Pacific/Easter',
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294 '-300,0' : 'America/Bogota',
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295 '-300,1' : 'America/New_York',
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296 '-270,0' : 'America/Caracas',
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297 '-240,1' : 'America/Halifax',
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298 '-240,0' : 'America/Santo_Domingo',
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299 '-240,1,s' : 'America/Santiago',
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300 '-210,1' : 'America/St_Johns',
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301 '-180,1' : 'America/Godthab',
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302 '-180,0' : 'America/Argentina/Buenos_Aires',
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303 '-180,1,s' : 'America/Montevideo',
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304 '-120,0' : 'America/Noronha',
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305 '-120,1' : 'America/Noronha',
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306 '-60,1' : 'Atlantic/Azores',
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307 '-60,0' : 'Atlantic/Cape_Verde',
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308 '0,0' : 'UTC',
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309 '0,1' : 'Europe/London',
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310 '60,1' : 'Europe/Berlin',
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311 '60,0' : 'Africa/Lagos',
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312 '60,1,s' : 'Africa/Windhoek',
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313 '120,1' : 'Asia/Beirut',
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314 '120,0' : 'Africa/Johannesburg',
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315 '180,0' : 'Asia/Baghdad',
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316 '180,1' : 'Europe/Moscow',
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317 '210,1' : 'Asia/Tehran',
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318 '240,0' : 'Asia/Dubai',
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319 '240,1' : 'Asia/Baku',
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320 '270,0' : 'Asia/Kabul',
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321 '300,1' : 'Asia/Yekaterinburg',
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322 '300,0' : 'Asia/Karachi',
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323 '330,0' : 'Asia/Kolkata',
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324 '345,0' : 'Asia/Kathmandu',
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325 '360,0' : 'Asia/Dhaka',
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326 '360,1' : 'Asia/Omsk',
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327 '390,0' : 'Asia/Rangoon',
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328 '420,1' : 'Asia/Krasnoyarsk',
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329 '420,0' : 'Asia/Jakarta',
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330 '480,0' : 'Asia/Shanghai',
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331 '480,1' : 'Asia/Irkutsk',
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332 '525,0' : 'Australia/Eucla',
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333 '525,1,s' : 'Australia/Eucla',
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334 '540,1' : 'Asia/Yakutsk',
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335 '540,0' : 'Asia/Tokyo',
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336 '570,0' : 'Australia/Darwin',
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337 '570,1,s' : 'Australia/Adelaide',
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338 '600,0' : 'Australia/Brisbane',
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339 '600,1' : 'Asia/Vladivostok',
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340 '600,1,s' : 'Australia/Sydney',
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341 '630,1,s' : 'Australia/Lord_Howe',
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342 '660,1' : 'Asia/Kamchatka',
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343 '660,0' : 'Pacific/Noumea',
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344 '690,0' : 'Pacific/Norfolk',
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345 '720,1,s' : 'Pacific/Auckland',
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346 '720,0' : 'Pacific/Tarawa',
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347 '765,1,s' : 'Pacific/Chatham',
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348 '780,0' : 'Pacific/Tongatapu',
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349 '780,1,s' : 'Pacific/Apia',
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350 '840,0' : 'Pacific/Kiritimati'
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351 };
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352
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353 if (typeof exports !== 'undefined') {
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354 exports.jstz = jstz;
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355 } else {
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356 root.jstz = jstz;
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357 }
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358 })(this);
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