$(document).ready(function(){    //限制字符个数        $(".act_p2").each(function(){            var maxwidth = 20;            if($(this).text().length > maxwidth){                $(this).text($(this).text().substring(0,maxwidth));                $(this).html($(this).html()+'…');            }        });    });

http://www.zhangxinxu.com/wordpress/2009/09/%E5%85%B3%E4%BA%8E%E6%96%87%E5%AD%97%E5%86%85%E5%AE%B9%E6%BA%A2%E5%87%BA%E7%94%A8%E7%82%B9%E7%82%B9%E7%82%B9-%E7%9C%81%E7%95%A5%E5%8F%B7%E8%A1%A8%E7%A4%BA/