部分微信内置浏览器使用 window.location.href 重定向无效。
可使用HTML 的 <mate> 实现重定向，具体方案如下：
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function searchParam(name) {
var match = RegExp('[?&]' + name + '=([^&]*)').exec(window.location.search);
return match && decodeURIComponent(match[1].replace(/\+/g, ' '));
}
if (!searchParam('code')) {
const uri = encodeURIComponent(window.location.href);
const href = 'https://open.weixin.qq.com/connect/oauth2/authorize?appid=wx4e95556bd902571e&redirect_uri=' + uri + '&response_type=code&scope=snsapi_base&state=123#wechat_redirect';
const m = document.createElement('meta');
m.httpEquiv = "refresh";
m.content = "0;" + href;
document.head.appendChild(m);
}
</script>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width,initial-scale=1,user-scalable=0">
<title>Demo</title>
</head>
</body>
</html>
