Need help on String match

I am trying to show error message if user enters something else in the input box which is not expected.

The expected string is "games.yahoo.com" for example if "http://games.yahoo.com/game/ultimate-chess-flash.html" is passed it will return True.

Below is my code but it is not working. The problem part is "else if (inThere==false)". Any kind of help is appreciated.
Thank you.

<script type="text/javascript">
function validateForm()
{
var gname = document.forms["myForm"]["gname"];
var inThere = gname.match(/games.yahoo.com/g);

if (gname.value==null || gname.value=="")
{
alert("Can not be blank");
gname.focus()
return false;
}
else if (inThere==false)
{
alert("Enter Correct URL");
gname.focus()
return false;
}
else
{
var elem = document.getElementById('submit');
elem.style.display = 'none';

var elem = document.getElementById('myP');
elem.style.display = '';
}

}

</script>

<form name="myForm" onsubmit="return validateForm();" method="POST" action="test.php">
<label>Enter Game URL: </label>
<input name="gname" type="text" size="30" />
<button class="default blue" type="submit" id="submit"><span>Continue</span></button>
</form>

 

Try replacing match with indexOf method.
indexOf returns the position of the string in the other string. If not found, it will return -1.

function validateForm() {

var gname = document.forms["myForm"]["gname"];

var inThere = gname.indexOf("games.yahoo.com")

if (gname.value==null || gname.value=="")
{
alert("Can not be blank");
gname.focus()
return false;
}
else if (inThere == -1)
{
alert("Enter Correct URL");
gname.focus()
return false;
}
else
{
var elem = document.getElementById('submit');
elem.style.display = 'none';

var elem = document.getElementById('myP');
elem.style.display = '';
}

}

Code (markup):