JavaScript 中如何在考虑 .com.cn 的情况下获取一个 URL 的二级域名？

[mercury233]

将一级域名理解为 .com 或者 .com.cn 或者 .co.uk 等等

let addr1 = new URL("https://www.example.com/blahblah");
let addr2 = new URL("https://example.com/blahblah");
let addr3 = new URL("https://test.example.com/blahblah");
let addr4 = new URL("https://another.test.example.com/blahblah");

都需要取到二级域名 example.com

let addr1 = new URL("https://www.example.com.cn/blahblah");
let addr2 = new URL("https://example.com.cn/blahblah");
let addr3 = new URL("https://test.example.com.cn/blahblah");
let addr4 = new URL("https://another.test.example.com.cn/blahblah");

都需要取到二级域名 example.com.cn

[yuzo555]

https://publicsuffix.org/list/public_suffix_list.dat

[jucelin]

理论上提取不到的，给几个特殊的：
www.net.cn
edu.cn

当然也客户忽略这些，可以用列举法，如 https://whois.aliyun.com/js/domainparser.js