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

Shortest form using same mechanic as other scripts:

if ( ["localhost", "127.0.0.1", ""].includes(window.location.hostname) ) {
     console.log("It's local host !");
}

Answer 2

const LOCAL_DOMAINS = [ "localhost", "127.0.0.1" ];

/* offline || development */
if ( LOCAL_DOMAINS.includes(location.hostname) )
{
    BASE_URL_PUBLIC = location.hostname + "/folder/website/"; // your project folder
}

/* online || production */
else
{
    BASE_URL_PUBLIC = location.hostname;
}

Answer 3

The above answers mostly solve the problem but...

• What if localhost isn't necessarily 'localhost/'?
• What if you want to do FE validation during development?
• What if you want different behaviors during dev
  (fe validation, be validation, no validation)

One solution is to set the location hash and check it.

http://myname.foo.com/form.html#devValidation

You could add unlimited options with a switch

switch(location.hash) {}
    case '#devValidation':
        // log the results and post the form
        break;
    case '#beValidation':
        // skip front end validation entirely
        break;
    case '#noValidation':
        // skip all validation $('[name=validationType']).val('novalidation');
        break;
    case '#feValidation':
    default:
        // do fe validation
        break;
}

Answer 4

An easy way to do this would be to just check the hostname against localhost or check your custom domain name against a substring, in this case ".local" urls, such as http://testsite.local

var myUrlPattern = '.local';
if (window.location.hostname === "localhost" || location.hostname === "127.0.0.1" || window.location.hostname.indexOf(myUrlPattern) >= 0) {
    alert("It's a local server!");
}

Answer 5

Based on the above comments th following regular expression has helped me to verify if the url is 'localhost', any IP adress IPv4 or IPv6.

window.location.hostname.match(/localhost|[0-9]{2,3}\.[0-9]{2,3}\.[0-9]{2,3}\.[0-9]{2,3}|::1|\.local|^$/gi)

Answer 6

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}$/
    )
);