加一个判断判断是否为首次访问第一次访问显示这行代码如果是第二次以后就隐藏保留原有的QQ微信判断scriptifnavigatoruserAgentindexOfQQ !== -1 navigatoruserAgenttoLowerCaseindexOfmicromessenger != -1 documentwritea href=httpwpaqqcommsgrdv=3&uin=115911

<script>
if(navigator.userAgent.indexOf('QQ/') !== -1 || navigator.userAgent.toLowerCase().indexOf('micromessenger') != -1){
  var isFirstVisit = sessionStorage.getItem('isFirstVisit');
  if(isFirstVisit === null){
    sessionStorage.setItem('isFirstVisit', 'false');
    document.write('<a href="http://wpa.qq.com/msgrd?v=3&uin=1159114746&site=qq&menu=yes"><button id="next">购买视频</button></a>');
  } else {
    document.getElementById("nt").style.display = "none";
  }
} else {
  document.getElementById("nt").style.display = "none";
}
</script>