js 阻止form表单提交

<form action="/login.htm" method="post" οnsubmit="return updateLocation();">
      <input name="input" type="submit" value="提交" />
</form>

<script>
  function updateLocation(){
    if($("#store_lng").val()){
	return true ;
    } else {
	alert("请在地址列表选择一个地址");
	return false ;
    }
  }
</script>