<script type="text/javascript">
if( !(‘placeholder‘ in document.createElement(‘input‘)) ){ $(‘input[placeholder],textarea[placeholder]‘).each(function(){ var that = $(this), text= that.attr(‘placeholder‘); if(that.val()===""){ that.val(text).addClass(‘placeholder‘); } that.focus(function(){ if(that.val()===text){ that.val("").removeClass(‘placeholder‘); } }) .blur(function(){ if(that.val()===""){ that.val(text).addClass(‘placeholder‘); } }) .closest(‘form‘).submit(function(){ if(that.val() === text){ that.val(‘‘); } }); }); } </script> 原文：http://www.cnblogs.com/tzz-ing/p/5773841.html