input 输入密码回车自动提交数据

<script type="text/javascript" language="javascript" >
function passwd_check(){
    var name = $("#usrname").val()    ;
    var passwd = $("#passwd").val()    ;
        $.ajax({
       type: "POST",
       url: "cgi-bin/sys-login.cgi",
    timeout: 4000,
       data: {Name : name , Passwd : passwd },
       success: function(msg){
        //alert(msg);
        if(msg==0){
        window.location="/welcome.html";
        }
        else{
        new Dialog('你输入的密码或帐号错误...',{time:3000},{id:'dialog'}).show();
        }
   },
   error: function(){
    new Dialog('系统正忙，请稍候...',{time:3000},{id:'dialog'}).show();
   }
});
}
</script>

<input name="passwd" />