dart 正则表达式

https://juejin.im/post/5cb986355188251b194880bc
https://www.jb51.net/article/143017.htm
https://www.jb51.net/article/55456.htm

过滤html标签

RegExp exp = new RegExp(r'<[^>]+>');
String acontent = topicDatas.topic.content
  .replaceAll("<br>", "\n\n")
  .replaceAll("&nbsp", "")
  .replaceAll(exp, "");