Yes it populates your php variable successfully and returns the value in the variable 'data' used in the javascript below
<html>
<head>
<script type="text/javascript" src="jquery/jquery-1.3.2.min.js"></script>
<script type="text/javascript">
function myFunction(str){
var val = str;
alert(val);
$.ajax({
type: 'POST',
url: 'ROOMS.php',
data: {
source1 : val,
},
success: function( data ) {
$('#testTextArea').val(data);
}
});
}
</script>
<ul><li><a name="tabExe" onclick="myFunction('tabExe');" id="tabExe" href="javascript:void(0)">Executive Room</a></li></ul>
<textarea id="testTextArea"></textarea>
</body>
</html>