js将文本中的url替换成可点击的超链接

          function linkfilter(msg){              var url=msg;              var urlRegExp=new RegExp("((https|http|ftp|rtsp|mms|www)?:\/*\/*)[^\u4E00-\u9FA5]+" );              var newmsg="" ;              while (urlRegExp.exec(url)!= null){              var pipeiurl=urlRegExp.exec(url);              var newurl="<a href=" +pipeiurl[0]+ " target='_blank'>"+pipeiurl[0]+ "</a>";              var urllength=pipeiurl[0].length;              var start=url.indexOf(pipeiurl[0]);             newmsg+=url.substring(0,start)+newurl;             url=url.substring(start+urllength);             }              return msg=newmsg+url;         }