/*正则去除img中的css样式 */
function removeCss(content)
{
  let reg=/(style|class)="[^"]+"/gi;
  let img=/<img[^>]+>/gi;
  let res;
  if(img.test(content))
  {
    res = content.match(img);
   for(let i=0;i<res.length;i++){
        console.log(res[i].replace(reg,""));
        content=content.replace(res[i],res[i].replace(reg,""));
      }
  }
  return content.replace(/\<img/gi, '<img class="richImg"  ');
}