$('#flowfromid').bind("propertychange",function(){

//你的内容

});

$(document).ready(function () {
$("#txt_JumpPager").keydown(function (e) {
var curKey = e.which;
if (curKey == 13) {
$("#lbtn_JumpPager").click();
return false;
}
});
});

<input id="username" type="text" />
<input id="pass" type="password" />
<textarea id="msg" rows="2" cols="20"></textarea>
例子

<script type="text/javascript">
    $(function(){
        $(":input").focus(function(){
              $(this).addClass("focus");
        }).blur(function(){
              $(this).removeClass("focus");
        });
    })
</script>