A simple google search with 'javascript tic tac toe code'
will render this solution: http://www.javascriptkit.com/script/script2/tactoe.shtml
There are many other ways to skin this cat.
Here is a modification to your code using only a single array.
You can add the 'draw' logic easy enough.
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Tic-Tac-Toe Game</title>
<style>
th { border:1px solid black; height:75px; width:75px; font-size:2.5em; }
</style>
</head>
<body>
<table id="shape" border="1">
<tr>
<th onClick="setXO(0,0);" id="t0"></th>
<th onClick="setXO(0,1);" id="t1"></th>
<th onClick="setXO(0,2);" id="t2"></th>
</tr>
<tr>
<th onClick="setXO(1,0);" id="t3"></th>
<th onClick="setXO(1,1);" id="t4"></th>
<th onClick="setXO(1,2);" id="t5"></th>
</tr>
<tr>
<th onClick="setXO(2,0);" id="t6"></th>
<th onClick="setXO(2,1);" id="t7"></th>
<th onClick="setXO(2,2);" id="t8"></th>
</tr>
</table>
<script>
var arr = ['','','', '','','', '','',''];
var player=0;
function setXO(r,c){
var el;
player++;
var p = r*3+c;
if (player % 2 == 1) { arr[p] = 'O'; } else { arr[p] = 'X'; }
for (var p=0; p<9; p++) {
el = 't'+p; document.getElementById(el).innerHTML = arr[p];
}
if (checkWinner('O')) { alert('O wins'); };
if (checkWinner('X')) { alert('X wins'); };
}
function checkWinner(XO) {
var flag = false;
// across
if ( (arr[0] == XO) && (arr[0] == arr[1]) && (arr[1] == arr[2]) ) { flag = true; }
if ( (arr[3] == XO) && (arr[3] == arr[4]) && (arr[4] == arr[5]) ) { flag = true; }
if ( (arr[6] == XO) && (arr[6] == arr[7]) && (arr[7] == arr[8]) ) { flag = true; }
// down
if ( (arr[0] == XO) && (arr[0] == arr[3]) && (arr[3] == arr[6]) ) { flag = true; }
if ( (arr[1] == XO) && (arr[1] == arr[4]) && (arr[4] == arr[7]) ) { flag = true; }
if ( (arr[2] == XO) && (arr[2] == arr[5]) && (arr[5] == arr[8]) ) { flag = true; }
// diagonal
if ( (arr[0] == XO) && (arr[0] == arr[4]) && (arr[4] == arr[8]) ) { flag = true; }
if ( (arr[2] == XO) && (arr[2] == arr[4]) && (arr[4] == arr[6]) ) { flag = true; }
return flag;
}
</script>
</body>
</html>