【JavaScript】如何获取客户端IP地址？

使用这个库：request-ip

它按照如下顺序获取请求的IP地址：

1. X-Client-IP
2. X-Forwarded-For (Header may return multiple IP addresses in the format: “client IP, proxy 1 IP, proxy 2 IP”, so we take the first one.)
3. CF-Connecting-IP (Cloudflare)
4. Fastly-Client-Ip (Fastly CDN and Firebase hosting header when forwared to a cloud function)
5. True-Client-Ip (Akamai and Cloudflare)
6. X-Real-IP (Nginx proxy/FastCGI)
7. X-Cluster-Client-IP (Rackspace LB, Riverbed Stingray)
8. X-Forwarded, Forwarded-For and Forwarded (Variations of #2)
9. appengine-user-ip (Google App Engine)
10. req.connection.remoteAddress
11. req.socket.remoteAddress
12. req.connection.socket.remoteAddress
13. req.info.remoteAddress
14. Cf-Pseudo-IPv4 (Cloudflare fallback)
15. request.raw (Fastify)

如果最后都找不到，则返回null。