81 lines
3.0 KiB
JavaScript
81 lines
3.0 KiB
JavaScript
/**
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* @file
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* Timezone detection.
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*/
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(function ($, Drupal) {
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/**
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* Set the client's system time zone as default values of form fields.
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*
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* @type {Drupal~behavior}
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*/
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Drupal.behaviors.setTimezone = {
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attach(context, settings) {
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const $timezone = $(context).find('.timezone-detect').once('timezone');
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if ($timezone.length) {
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const tz = new Intl.DateTimeFormat().resolvedOptions().timeZone;
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// Ensure that the timezone value returned by the browser is supported
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// by the server.
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if (tz && $timezone.find(`option[value="${tz}"]`).length) {
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$timezone.val(tz);
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return;
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}
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const dateString = Date();
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// In some client environments, date strings include a time zone
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// abbreviation, between 3 and 5 letters enclosed in parentheses,
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// which can be interpreted by PHP.
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const matches = dateString.match(/\(([A-Z]{3,5})\)/);
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const abbreviation = matches ? matches[1] : 0;
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// For all other client environments, the abbreviation is set to "0"
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// and the current offset from UTC and daylight saving time status are
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// used to guess the time zone.
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const dateNow = new Date();
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const offsetNow = dateNow.getTimezoneOffset() * -60;
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// Use January 1 and July 1 as test dates for determining daylight
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// saving time status by comparing their offsets.
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const dateJan = new Date(dateNow.getFullYear(), 0, 1, 12, 0, 0, 0);
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const dateJul = new Date(dateNow.getFullYear(), 6, 1, 12, 0, 0, 0);
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const offsetJan = dateJan.getTimezoneOffset() * -60;
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const offsetJul = dateJul.getTimezoneOffset() * -60;
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let isDaylightSavingTime;
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// If the offset from UTC is identical on January 1 and July 1,
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// assume daylight saving time is not used in this time zone.
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if (offsetJan === offsetJul) {
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isDaylightSavingTime = '';
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}
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// If the maximum annual offset is equivalent to the current offset,
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// assume daylight saving time is in effect.
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else if (Math.max(offsetJan, offsetJul) === offsetNow) {
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isDaylightSavingTime = 1;
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}
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// Otherwise, assume daylight saving time is not in effect.
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else {
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isDaylightSavingTime = 0;
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}
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// Submit request to the system/timezone callback and set the form
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// field to the response time zone. The client date is passed to the
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// callback for debugging purposes. Submit a synchronous request to
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// avoid database errors associated with concurrent requests
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// during install.
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const path = `system/timezone/${abbreviation}/${offsetNow}/${isDaylightSavingTime}`;
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$.ajax({
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async: false,
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url: Drupal.url(path),
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data: { date: dateString },
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dataType: 'json',
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success(data) {
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if (data) {
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$timezone.val(data);
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}
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},
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});
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}
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},
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};
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})(jQuery, Drupal);
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