My html code:

```
<form id="room-from" method="post">
<input id="room" type="text" name="room" />
<input type="submit" id="save" name="save" />
</form>

```

when i press the save button if the room text field is empty a pop up should appear at the center of the screen and must say enter a room number.

jquery:

```
    $("#save").submit(function(){
    if ( $("#room").val() == "")
{

}
    });

```

I'm not sure how to do this.

Can anyone please help me out on this.