用JavaScript解决Placeholder的IE8兼容问题

<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>

　　非常棒