<html><head><title>Regulaaravaldis</title></head>
<body>
 <script>
   var r=new RegExp("kass", "g");
   lause1="ks kass lks le silla, see kass oli tume."; 
   lause2=lause1.replace(r, "koer");
   document.writeln(lause2);
 </script>
</body></html>
