woocommerce/assets/js/frontend/country-select.js

jQuery(document).ready(function($) {

	// wc_country_select_params is required to continue, ensure the object exists
	if (typeof wc_country_select_params === "undefined")
		return false;

	/* State/Country select boxes */
	var states_json = wc_country_select_params.countries.replace(/"/g, '"');
	var states = $.parseJSON( states_json );

	$('select.country_to_state, input.country_to_state').change(function(){

		var country = $(this).val();

		var $statebox = $(this).closest('div').find('#billing_state, #shipping_state, #calc_shipping_state');
		var $parent = $statebox.parent();

		var input_name = $statebox.attr('name');
		var input_id = $statebox.attr('id');
		var value = $statebox.val();
		var placeholder = $statebox.attr('placeholder');

		if (states[country]) {
			if (states[country].length == 0) {

				$statebox.parent().hide().find('.chosen-container').remove();
				$statebox.replaceWith('<input type="hidden" class="hidden" name="' + input_name + '" id="' + input_id + '" value="" placeholder="' + placeholder + '" />');

				$('body').trigger('country_to_state_changed', [country, $(this).closest('div')]);

			} else {

				var options = '';
				var state = states[country];
				for(var index in state) {
					options = options + '<option value="' + index + '">' + state[index] + '</option>';
				}
				$statebox.parent().show();
				if ($statebox.is('input')) {
					// Change for select
					$statebox.replaceWith('<select name="' + input_name + '" id="' + input_id + '" class="state_select" placeholder="' + placeholder + '"></select>');
					$statebox = $(this).closest('div').find('#billing_state, #shipping_state, #calc_shipping_state');
				}
				$statebox.html( '<option value="">' + wc_country_select_params.i18n_select_state_text + '</option>' + options);

				$statebox.val(value);

				$('body').trigger('country_to_state_changed', [country, $(this).closest('div')]);

			}
		} else {
			if ($statebox.is('select')) {

				$parent.show().find('.chosen-container').remove();
				$statebox.replaceWith('<input type="text" class="input-text" name="' + input_name + '" id="' + input_id + '" placeholder="' + placeholder + '" />');

				$('body').trigger('country_to_state_changed', [country, $(this).closest('div')]);

			} else if ($statebox.is('.hidden')) {

				$parent.show().find('.chosen-container').remove();
				$statebox.replaceWith('<input type="text" class="input-text" name="' + input_name + '" id="' + input_id + '" placeholder="' + placeholder + '" />');

				$('body').trigger('country_to_state_changed', [country, $(this).closest('div')]);

			}
		}

		$('body').trigger('country_to_state_changing', [country, $(this).closest('div')]);

	});

});