I need a bit of code for a website that pings another website and shows a green dot if its up and red dot if its down?

I need a bit of code for a website that pings another website and shows a
green dot if its up and red dot if its down?

Ive been trying to do this for a little while now but always come up with
errors etc would prefer javascript put not too picky - I need a bit of
code for a website that pings another website and shows a green dot if its
up and red dot if its down? the code is for a website im making which i
will list all the websites ive made on different domains and then will
leave it open 24/7 and i will know instantly if one of the sites go
offline. Preferably the code will refresh its self every 15 or so seconds.
Thanks in advance :)