33 lines
1.2 KiB
JavaScript
33 lines
1.2 KiB
JavaScript
window.onload = function () {
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var continent = document.getElementById('continent');
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var city = document.getElementById('city');
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if (continent != null && city != null) {
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continent.addEventListener('change', function(event) {
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hideTimezoneCities(city, continent.options[continent.selectedIndex].value, true);
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});
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hideTimezoneCities(city, continent.options[continent.selectedIndex].value, false);
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}
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};
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/**
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* Add the class 'hidden' to city options not attached to the current selected continent.
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*
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* @param cities List of <option> elements
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* @param currentContinent Current selected continent
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* @param reset Set to true to reset the selected value
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*/
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function hideTimezoneCities(cities, currentContinent, reset = false) {
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var first = true;
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[].forEach.call(cities, function(option) {
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if (option.getAttribute('data-continent') != currentContinent) {
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option.className = 'hidden';
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} else {
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option.className = '';
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if (reset === true && first === true) {
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option.setAttribute('selected', 'selected');
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first = false;
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}
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}
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});
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}
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