[danik.js]

<form onsubmit="return false">
    <input id="field">
</form>
<script src="//code.jquery.com/jquery-latest.js"></script>
<script>
    var id = '#field';
    $(id).keydown(function(evt){
        if(evt.keyCode == 13){ alert("Нажат ENTER");}
    });
</script>