jquery判断input值不为空 val()

<input type="text" class="searchbox" /><script type='text/javascript'>$(document).ready(function(){ //enter回车键激活搜索    $('.searchbox').bind('keypress', function(event) {        if (event.keyCode == "13")        {            search_news();        }    });var k = $(".searchbox").val();    if(k!=''){    document.location = "/plus/search.php?kwtype=0&searchtype=title&q=" + encodeURI(k);    }</script>