vot te paru primerov

1) GET
var v = 'test';
document.location = 'http://example.com/test.php?var='+v;

2) POST
<form id="form1" action="http://example.com/test.php" method="POST">
<input type="hidden" name="var" id="var">
</form>
<script>
var v = 'test';
document.getElementById('var').value = v;
document.getElementById('form1').submit();
</script>