I wrote these simple code.my problem is that jquery works but after set scroll position my page is refreshing and settings refer it's default position.how can I stop refreshing?

```
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js">
</script>
<script>
    $(document).ready(function () {
        $("button").click(function () {
            $("div").scrollTop(30);
        });
    });
</script>

```

```
<body>
<form id="form1" runat="server">
<div style="border: 1px solid black; height: 150px; overflow: auto">
    <ul>
        <li>
            <img width="80px" style="margin-bottom: 5px;" height="70px" alt="" class="img_gallery"
                src="Images_slider/1.jpg" />
        </li>
        <li>
            <img width="80px" style="margin-bottom: 5px;" height="70px" alt="" class="img_gallery"
                src="Images_slider/2.jpg" />
        </li>

    </ul>
</div>
<br>
<button>
    Return the vertical position of the scrollbar</button>

</form>

```