[jQuery] Ajax ,dataType and success

[jQuery] Ajax ,dataType and success


this is my code, a normal code as the examples on jquery.com
ajax.php can only echo "OK1", "OK2" or "KO", so I wonder why none of
the if in the success function work ? but the alert before works well
and i set dataType = text just to be sure. It's like mess is another
type of variable or what ? Thank you
$.ajax({
type:"POST",
url:"ajax.php",
data:"act=buy,
cache:false,
dataType: "text",
beforeSend: function(){
// Loading
},
success: function(mess){
var txt = mess;
alert(txt);
if(txt=="OK1")
alert(txt);
if(txt=="OK2")
alert(txt);
if(txt=="KO")
alert(txt);
},
error: function(){
// Errore
}
});