[Ajax] Zwei statische Werte übergeben sowie ausführen ???

var myRequest = new Request({
 method: 'post',
 url: 'ajax_test.php',
 onSuccess: function (txt,xml){
 alert (txt);
 },
 onFailure: function (txt){
 alert (txt);
 }
});
myRequest.send({
 data: {
 'str' : 'xxx'
 }
});

$('usrID').value = txt;

<span id="btnID">klick</span>

<form action="" id="formID" name="form" method="post">
 <input type="text" name="usr" id="usrID" />
 <input type="text" name="pwd" id="pwdID" />
</form>

<script type="text/javascript">
 $('btnID').addEvent('click', function(event){
 $('usrID').value = 'xxx';
 $('pwdID').value = 'xxx';
 $('formID').submit();
 });
</script>

document.getElementById("id-des-elements-name").value = "name";
document.getElementbyId("id-des-elements-pass").value = "passwort";

var xhr = new XMLHttpRequest;
xhr.open("POST", "ajax_test.php", true);
xhr.addEventListener("load", function() { alert(this.responseText); });
xhr.addEventListener("error", function() { alert("fehler"); });
xhr.send("str=xxx");

<form action="geh/wo/hin.php" id="formID" name="form" method="post">