var $ = function(f){return document.getElementById(f);} 

function check_con(){
          var f= "content"; //需要检测的内容

             var kw;
          var mess = $(f).value.replace(/<[^>]+>/g,"");//去掉所有的html标记;
          var clearhtml =/<(?:.|s)*?>|&nbsp;/g;//去掉所有的html标记和 &nbsp;
          mess = html.replace(/<[^>]+>/g,"");//去掉所有的html标记;
          mess = mess.replace(/(^\s+)|(\s+$)/g,"");//去掉前后空格
          mess = mess.replace(/\s/g,"");//去除文章中间空格
          mess = mess .replace(clearhtml,'');
      for(var i=0;i<mess.length;i++){
        kw = mess[i].toLowerCase();
        if(kw =='h'){ var http = kw+mess[i+1]+mess[i+2]+mess[i+3];if(http.toLowerCase() == 'http'){alert('存在网址');return false;}}
        if(kw =='.'){
          var url = mess[i+1]+mess[i+2]+mess[i+3]; var surl = mess[i+1]+mess[i+2]; var tourl = mess[i+1]+mess[i+2]+mess[i+3]+mess[i+4];
          url = url.toLowerCase();surl =surl.toLowerCase();tourl =tourl.toLowerCase();
          if(url == 'com'|| url=='net' || url=='org'|| surl == 'cn' ||surl=='cc' || tourl=='info'  || tourl=='name' || surl=='uk') alert('存在网址');return false;}
        if(kw == 'q' && mess[i+1].toLowerCase()=='q' || mess[i+1].toLowerCase()==':'){alert('存在QQ');return false;}
        if(kw == '@' && mess[i+1].toLowerCase()=='q'){alert('存在邮箱');return false;}
       }
    }