jquery show() 回调有关问题(2)

        var $this = $(this);

        if( $this.is(':visible') ) {

          if( $this.data('placeholder') ) {
            var $ol = $this.data('placeholder');
            $ol.css(calcPositionCss($this));
            return true;
          }

          var possible_line_height = {};
          if( !$this.is('textarea') && $this.css('height') != 'auto') {
            possible_line_height = { lineHeight: $this.css('height'), whiteSpace: 'nowrap' };
          }

          var ol = $('<label />')
            .text($this.attr('placeholder'))
            .addClass(config.cls)
            .css($.extend({
              position:'absolute',
              display: 'inline',
              float:'none',
              overflow:'hidden',
              textAlign: 'left',
              color: config.color,
              cursor: 'text',
              paddingTop: $this.css('padding-top'),
              paddingRight: $this.css('padding-right'),
              paddingBottom: $this.css('padding-bottom'),
              paddingLeft: $this.css('padding-left'),
              fontSize: $this.css('font-size'),
              fontFamily: $this.css('font-family'),
              fontStyle: $this.css('font-style'),
              fontWeight: $this.css('font-weight'),
              textTransform: $this.css('text-transform'),
              backgroundColor: 'transparent',
              zIndex: 99
            }, possible_line_height))
            .css(calcPositionCss(this))