How to check with javascript if connection is local host?

Question

I want to have a check in my javascript if the page loading up is on my local machine.

The reason why I want to do that is that when I developing I like to make sure

Answer 1

That's how it get checked in React, register service worker, good way to check if you are on localhost by checking hostname, including localhost and IPv6, and matching start with 127:

const isLocalhost = Boolean(
    window.location.hostname === 'localhost' ||
    // [::1] is the IPv6 localhost address.
    window.location.hostname === '[::1]' ||
    // 127.0.0.1/8 is considered localhost for IPv4.
    window.location.hostname.match(
        /^127(?:\.(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)){3}$/
    )
);