<form method="post"> <input type="text"/> <input type="submit"/> </form>
<form method="post" onkeypress="if(event.keyCode == 13) return false;"> <input type="text"/> <input type="submit"/> </form>
<form action="#" method="post"> <input type="text"/><br /> <input type="text"/> <input type="button" value="submit" onclick="this.form.submit();"/> </form>
<form method="post"> <input type="text"/> <input type="submit"/> </form> <script type="text/javascript"> document.forms[0].onkeypress = function (a) { a = a || window.event; if (a.keyCode == 13 || a.which == 13) a.preventDefault ? a.preventDefault() : a.returnValue = false }; </script>