if($_GET["tekst"]=="1"){
echo "siaki$ napis 1<br>";
}
else echo "<a href='index.php?tekst=1'>link</a><br> ";


if($_GET["tekst"]=="2"){
echo "siaki$ napis 2<br>";
}
else echo "<a href='index.php?tekst=2'>link</a><br> ";

function gup( name ) {
  name = name.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
  var regexS = "[\\?&]"+name+"=([^&#]*)";
  var regex = new RegExp( regexS );
  var results = regex.exec( window.location.href );
  if( results == null )
    return "";
  else
    return results[1];
}

var tekst = gup("tekst");
if(tekst=="1"){
document.wrtie("siaki$ napis 1<br>");
} else {
document.write("<a href='index.php?tekst=1'>link</a><br>");
}

if(tekst=="2"){
document.write("siaki$ napis 2<br>");
} else {
  document.write("<a href='index.php?tekst=2'>link</a><br>");
}