I want to underline existing inner html but existing value is replaced

Tried but existing value is replaced with new one

```
<script>
    $(document).ready(function()
    {
        $('li').click(function()
        {
            $(this).html('<strike> completed</strike');
        })
    });
</script>
<Ul>
    <li>Milan</li>
    <li>Katwal</li>
    <li>done</li>
</Ul>

```

The existing element should be underline