jquery判断input值不为空的方法

<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>

$(function() {      $(".searchbox").blur(function() {        if ($(".searchbox").val() == "")        { $(".searchbox").focus(); }        else          alert($(".searchbox").val());      });    });