74 lines
2.7 KiB
JavaScript
74 lines
2.7 KiB
JavaScript
// Copyright The IETF Trust 2021, All Rights Reserved
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/*
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Timezone selection handling. Relies on the moment.js library.
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To use, create one (or more) select inputs with class "tz-select". When the initialize()
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method is called, the options in the select will be replaced with the recognized time zone
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names. Time zone can be changed via the select input or by calling the use() method with
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the name of a time zone (or 'local' to guess the user's local timezone).
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*/
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window.ietf_timezone; // public interface
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(function () {
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'use strict';
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// Callback for timezone change - called after current_timezone is updated
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var timezone_change_callback;
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var current_timezone;
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// Select timezone to use. Arg is name of a timezone or 'local' to guess local tz.
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function use_timezone (newtz) {
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// Guess local timezone if necessary
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if (newtz.toLowerCase() === 'local') {
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newtz = moment.tz.guess()
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}
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if (current_timezone !== newtz) {
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current_timezone = newtz
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// Update values of tz-select inputs but do not trigger change event
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$('select.tz-select').val(newtz)
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if (timezone_change_callback) {
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timezone_change_callback(newtz)
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}
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}
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}
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/* Initialize timezone system
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*
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* This will set the timezone to the value of 'current'. Set up the tz_change callback
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* before initializing.
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*/
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function timezone_init (current) {
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var tz_names = moment.tz.names()
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var select = $('select.tz-select')
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select.empty()
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$.each(tz_names, function (i, item) {
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if (current === item) {
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select.append($('<option/>', {
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selected: 'selected', html: item, value: item
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}))
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} else {
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select.append($('<option/>', {
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html: item, value: item
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}))
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}
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})
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select.on("change", function () {use_timezone(this.value)});
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/* When navigating back/forward, the browser may change the select input's
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* value after the window load event. It does not fire the change event on
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* the input when it does this. The pageshow event occurs after such an update,
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* so trigger the change event ourselves to be sure the UI stays consistent
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* with the timezone select input. */
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window.addEventListener('pageshow', function(){select.trigger("change"); })
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use_timezone(current);
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}
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// Expose public interface
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ietf_timezone = {
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get_current_tz: function() {return current_timezone},
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initialize: timezone_init,
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set_tz_change_callback: function(cb) {timezone_change_callback=cb},
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use: use_timezone
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}
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})(); |