<input type="text" />

<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>

再给大家分享一个更简洁的方法

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