<script>
$(function() {
  $('#submit').click(function() {
    var d = {};
    var t = $('form').serializeArray();
    $.each(t, function() {
      d[this.name] = this.value;
    });
    alert(JSON.stringify(d));
  });
});
</script>
<form>
<input id="a1" type="input" value="" name="a1"><br>
<input id="a2" type="input" value="" name="a2"><br>
<input id="a3" type="input" value="" name="a3"><br>
<input id="a4" type="input" value="" name="a4"><br>
<select id="se" name="se">
<option value="0">選項1</option>
<option value="1">選項2</option>
</select><br>
<input id="submit" type="button" value="提交" name="submit">
</form>