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POHow to avoid 3 ajax calls?
 

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    <p>I wrote some code that filters a province/state select field after you choose a country:</p> <pre><code> var cache = {}; function updateProvinceOptions($select, values, initial) { for(i in values) { $select.append('&lt;option value="'+values[i][0]+'"&gt;'+values[i][1]+'&lt;/option&gt;'); } $select.val(initial).trigger('change'); } $('&lt;select class="province" /&gt;').insertBefore('.province').change(function() { // insert select boxes beside hidden province inputs $(this).siblings('input.province').val($(this).val()); // update hidden input with current value }); $('.country').change(function() { var $countrySel = $(this); var $provSel = $countrySel.parent().parent().next().children('td').children('select.province'); var $provInput = $provSel.siblings('input.province'); var country = $countrySel.val(); var province = $provInput.val(); $provSel.empty(); if(country in cache) { updateProvinceOptions($provSel, cache[country], province); } else { $provSel.addClass('loading'); $.getJSON('/get-provinces.json', {'country':country}, function(provinces) { $provSel.removeClass('loading'); cache[country] = provinces; updateProvinceOptions($provSel, provinces, province); }); } }).trigger('change'); </code></pre> <p>It even caches the results so that if you, say, choose Canada, then US, and then Canada again, it doesn't have to hit the server for the list of Canadian provinces a second time. However, I'm displaying 3 of these on the page at the same time. When the page first loads, there's nothing in cache, so all 3 of em hit the server for a list of provinces because none of the ajax calls have returned yet. </p> <p>Is there a relatively simple way to tell it to "wait" if an ajax call for that country is already in progress? Or should I even bother?</p>
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