$（’＃mobile_phone_network option：selected’）。val（）我没有经过测试，但是应该可以使用。很简单，它将给您一些想法
**HTML**<div id="countryWrap"><select id="country" name="country"></select></div><div id="stateWrap"><select id="state" name="state"></select></div><div id="cityWrap"><select id="city" name="city"></select></div><script>$(document).ready(function(){ $('#country').change(function(){ loadState($(this).find(':selected').val()) }) $('#state').change(function(){ loadCity($(this).find(':selected').val()) })})function loadCountry(){ $.ajax({ type: "POST", url: "ajax/ajax.php", data: "get=country" }).done(function( result ) { $(result).each(function(){ $("#country").append($('<option>', { value: this.id, text: this.name, })); }) });}function loadState(countryId){ $("#state").children().remove() $.ajax({ type: "POST", url: "ajax/ajax.php", data: "get=state&countryId=" + countryId }).done(function( result ) { $(result).each(function(){ $("#state").append($('<option>', { value: this.id, text: this.name, })); }) });}function loadCity(stateId){ $("#city").children().remove() $.ajax({ type: "POST", url: "ajax/ajax.php", data: "get=city&stateId=" + stateId }).done(function( result ) { $(result).each(function(){ $("#city").append($('<option>', { value: this.id, text: this.name, })); }) });}// init the countriesloadCountry();</script>**ajax.php**$countryId = isset($_POST['countryId']) ? $_POST['countryId'] : 0;$stateId = isset($_POST['stateId']) ? $_POST['stateId'] : 0;$command = isset($_POST['get']) ? $_POST['get'] : "";switch($command){case "country":$statement = "SELECT id, name FROM country";break;case "state":$statement = "SELECt id, name FROM state WHERe country_id=".(int)countryId;break;case "city":$statement = "SELECt id, name FROM country WHERe state_id=".(int)stateId;break;default:break;}$sth = $dbh->prepare($statement);$sth->execute();$result = $sth->fetchAll();echo json_enpre($result);exit();
