japan_address_api.html

<input type="number" id="zip">
<button type="button" onClick="search_addr();">住所検索</button>

<input type="text" id="address">
<!-- 스크립트를 로드 -->
<script src="//api.zipaddress.net/sdk/zipaddr.min.js" async></script>
<script>
var search_addr = function(){
    var $zip = $('#zip');
    var zip = $zip.val();
    // 일본 우편번호는 7자리로 고정되어있다.
    // sample 6800001
    if(zip && zip.length === 7){
        ZA.request(zip, function(data, err){
            var $address = $('#address');

            if(err){
                $address.val('');
                $zip.focus();
                return alert(data.message);
            }

            $address.val(data.fullAddress);
            $address.focus();
        });
    }else{
        alert('郵便番号に誤りがあります。');
        $zip.focus();
    }
};
</script>