<script> 
  document.onkeydown=function(event){ 
    e = event ? event :(window.event ? window.event : null); 
    if(e.keyCode==13){ 
      //执行的方法 
      alert('回车检测到了'); 
    } 
  } 
</script> 
<script>
 document.onkeydown=function(event){
 e = event ? event :(window.event ? window.event : null);
 if(e.keyCode==13){
  //执行的方法
  alert('回车检测到了');
 }
 }
</script>

<script> 
  $(document).ready(function(){ 
    $("按下回车的控件").keydown(function(e){ 
      var curKey = e.which; 
      if(curKey == 13){ 
        $("#回车事件按钮控件").click(); 
        return false; 
      } 
    }); 
  }); 
</script>