why does this code not work on internet explorer?
function sendmessage()
{
message = document.getElementById("message");
messagetext = message.value;
message.value = "";
if (window.XMLHttpRequest) {
check = new XMLHttpRequest();
} else if (window.ActiveXObject) {
isIE = true;
check = new ActiveXObject("Microsoft.XMLHTTP");
}
check.onreadystatechange = function() {
getupdate();
}
check.open("GET", "<?=$PHP_SELF?>?do=send&message=" + escape(messagetext), true);
check.send(null);
}