How to remove subdomains from domains using javascript

Question

I am starting with domains that look like this:

www.exemple.com
main.testsite.com
www.ex-emple.com.ar
main.test-site.co.uk
en.tour.mysite.nl
www.ip.com
www.one.lv

and I need to remove the subdomains to get values that look like this:

exemple.com
testsite.com
ex-emple.com.ar
test-site.co.uk
mysite.nl
ip.com
one.lv

other top level domains:

.ac
.ad
.ae
.af
.ag
.ai
.al
.am
.ao
.aq
.ar
.as
.asia
.at
.au
.aw
.ax
.az
.ba
.bb
.bd
.be
.bf
.bg
.bh
.bi
.bj
.bm
.bn
.bo
.br
.bs
.bt
.bw
.by
.bz
.ca
.cc
.cd
.cf
.cg
.ch
.ci
.ck
.cl
.cm
.cn
.co
.co.ao
.co.ba
.co.bw
.co.cc
.co.ck
.co.cr
.co.fk
.co.id
.co.il
.co.im
.co.in
.co.jp
.co.ke
.co.kr
.co.ls
.co.ma
.co.mz
.co.nl
.co.nz
.co.th
.co.tz
.co.ug
.co.uk
.co.uz
.co.ve
.co.vi
.co.za
.co.zm
.co.zw
.com
.com.af
.com.ag
.com.ai
.com.al
.com.ar
.com.au
.com.aw
.com.az
.com.bb
.com.bd
.com.bh
.com.bi
.com.bm
.com.bn
.com.bo
.com.br
.com.bs
.com.bt
.com.by
.com.bz
.com.cm
.com.cn
.com.co
.com.cu
.com.cv
.com.cy
.com.do
.com.dz
.com.ec
.com.ee
.com.eg
.com.es
.com.et
.com.fj
.com.ge
.com.gh
.com.gi
.com.gl
.com.gn
.com.gp
.com.gr
.com.gt
.com.gu
.com.hk
.com.hn
.com.hr
.com.ht
.com.jm
.com.jo
.com.kg
.com.kh
.com.ki
.com.kw
.com.ky
.com.kz
.com.lb
.com.lc
.com.lk
.com.lr
.com.lv
.com.ly
.com.mg
.com.mk
.com.mm
.com.mo
.com.mt
.com.mu
.com.mv
.com.mw
.com.mx
.com.my
.com.na
.com.nf
.com.ng
.com.ni
.com.np
.com.nr
.com.om
.com.pa
.com.pe
.com.pg
.com.ph
.com.pk
.com.pl
.com.pr
.com.ps
.com.pt
.com.py
.com.qa
.com.ro
.com.sa
.com.sb
.com.sc
.com.sg
.com.sl
.com.sn
.com.sv
.com.sy
.com.tj
.com.tn
.com.tr
.com.tt
.com.tw
.com.ua
.com.uy
.com.uz
.com.vc
.com.ve
.com.vi
.com.vn
.com.ye
.cr
.cv
.cx
.cy
.cz
.de
.dj
.dk
.dm
.do
.dz
.ec
.edu
.ee
.eg
.es
.eu
.fi
.fj
.fk
.fm
.fo
.fr
.ga
.gd
.ge
.gf
.gg
.gh
.gi
.gl
.gm
.gn
.gov
.gp
.gq
.gr
.gs
.gt
.gu
.gy
.hk
.hm
.hn
.hr
.ht
.hu
.id
.ie
.il
.im
.in
.io
.iq
.is
.it
.je
.jm
.jo
.jp
.ke
.kg
.kh
.ki
.km
.kn
.kr
.kw
.ky
.kz
.la
.lb
.lc
.li
.lk
.lr
.ls
.lt
.lu
.lv
.ly
.ma
.mc
.md
.me
.mg
.mil
.mk
.ml
.mm
.mn
.mo
.mobi
.mp
.mq
.mr
.ms
.mt
.mu
.mv
.mw
.mx
.my
.na
.name
.nc
.ne
.ne.jp
.net
.net.ck
.net.cm
.net.in
.nf
.ng
.ni
.nl
.no
.np
.nr
.nu
.nz
.og.ao
.om
.or.th
.org
.org.ck
.org.cn
.org.ls
.pa
.pe
.pf
.pg
.ph
.pk
.pl
.pm
.pn
.pr
.pro
.ps
.pt
.py
.qa
.re
.ro
.rs
.ru
.rw
.sa
.sb
.sc
.se
.sg
.sh
.si
.sk
.sl
.sm
.sn
.so
.sr
.st
.su
.sv
.sy
.tc
.td
.tf
.tg
.th
.tj
.tk
.tl
.tm
.tn
.to
.tr
.tt
.tv
.tw
.tz
.ua
.ug
.uk
.us
.uy
.uz
.vc
.ve
.vg
.vi
.vn
.vu
.wf
.ws
.xxx
.ye
.yt
.za
.zm
.zw

Answer 1

psl library on npm does what you are asking.

const domain = psl.get(host);

It uses Mozilla's Public suffix list which is considered the official resource for this information.

Answer 2

var result = string.replace(/^[^.]+\./g, "");