Extract Hostname Name from String

Extract hostname name from string

There is no need to parse the string, just pass your URL as an argument to URL constructor:

const url = 'http://www.youtube.com/watch?v=ClkQA2Lb_iE';
const { hostname } = new URL(url);

console.assert(hostname === 'www.youtube.com');

Extract host name/domain name from URL string

You can use the java.net.URI-class to extract the hostname from the string.

Here below is a method from which you can extract your hostname from a string.

public String getHostName(String url) {
    URI uri = new URI(url);
    String hostname = uri.getHost();
    // to provide faultproof result, check if not null then return only hostname, without www.
    if (hostname != null) {
        return hostname.startsWith("www.") ? hostname.substring(4) : hostname;
    }
    return hostname;
}

This above gives you the hostname, and is faultproof if your hostname does start with either hostname.com/... or www.hostname.com/..., which will return with 'hostname'.

If the given url is invalid (undefined hostname), it returns with null.

Extract hostname from a given domain string and remove extension and www

You can use built in URL.hostname and replace www.

console.log(new URL('https://example.com/').hostname.replace('www.', ''))
console.log(new URL('https://www.example.com/').hostname.replace('www.', ''))

URL can be used in most of the browsers https://caniuse.com/?search=URL

Get domain name from given url

If you want to parse a URL, use java.net.URI. java.net.URL has a bunch of problems -- its equals method does a DNS lookup which means code using it can be vulnerable to denial of service attacks when used with untrusted inputs.

"Mr. Gosling -- why did you make url equals suck?" explains one such problem. Just get in the habit of using java.net.URI instead.

public static String getDomainName(String url) throws URISyntaxException {
    URI uri = new URI(url);
    String domain = uri.getHost();
    return domain.startsWith("www.") ? domain.substring(4) : domain;
}

should do what you want.

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Though It seems to work fine, is there any better approach or are there some edge cases, that could fail.

Your code as written fails for the valid URLs:

• httpfoo/bar -- relative URL with a path component that starts with http.
• HTTP://example.com/ -- protocol is case-insensitive.
• //example.com/ -- protocol relative URL with a host
• www/foo -- a relative URL with a path component that starts with www
• wwwexample.com -- domain name that does not starts with www. but starts with www.

Hierarchical URLs have a complex grammar. If you try to roll your own parser without carefully reading RFC 3986, you will probably get it wrong. Just use the one that's built into the core libraries.

If you really need to deal with messy inputs that java.net.URI rejects, see RFC 3986 Appendix B:

Appendix B. Parsing a URI Reference with a Regular Expression

As the "first-match-wins" algorithm is identical to the "greedy"
disambiguation method used by POSIX regular expressions, it is
natural and commonplace to use a regular expression for parsing the
potential five components of a URI reference.

The following line is the regular expression for breaking-down a
well-formed URI reference into its components.

  ^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?
   12            3  4          5       6  7        8 9

The numbers in the second line above are only to assist readability;
they indicate the reference points for each subexpression (i.e., each
paired parenthesis).

Java regex to extract host name and domain name from a URL

You may use this regex with optional matches and capture groups:

^(?:\w+://)?((?:[^./?#]+\.)?([^/?#]+))

RegEx Demo

RegEx Details:

• ^: Start
• (?:\w+://)?: Optionally match scheme names followed by ://
• (: Start capture group #1
  
  • (?:[^./?#]+\.)?: Optionally match first part of domain name using a non-capture group
  • ([^/?#]+): Match 1+ of any character that is not /, ?, # in capture group #2
• ): End capture group #1

How to Extract Domain name from string with Regex in C#?

According to Lidqy answer, I wrote this function, which I think supports most possible situations, and if the input value is out of this, you can make it an exception.

public static string ExtractDomainName(string Url)
        {
            var regex = new Regex(@"^((https?|ftp)://)?(www\.)?(?<domain>[^/]+)(/|$)");

            Match match = regex.Match(Url);

            if (match.Success)
            {
                string domain = match.Groups["domain"].Value;
                int freq = domain.Where(x => (x == '.')).Count();
                while (freq > 2)
                {
                    if (freq > 2)
                    {
                        var domainSplited = domain.Split('.', 2);
                        domain = domainSplited[1];
                        freq = domain.Where(x => (x == '.')).Count();
                    }
                }
                return domain;
            }
            else
            {
                return String.Empty;
            }
        }

Extract domain name from string using PHP

Use below Regular Expression for extracting domain name from string, Try:

$input = 'AmericanSwan.com Indian Websites';
preg_match_all('#[-a-zA-Z0-9@:%_\+.~\#?&//=]{2,256}\.[a-z]{2,4}\b(\/[-a-zA-Z0-9@:%_\+.~\#?&//=]*)?#si', $input, $result);
echo $result[0][0]; //$result will give list of all domain names of string, you can also loop through it

Output:

AmericanSwan.com

How to extract hostname and port from URL string?

Without reinventing the wheel, you can simply leverage java.net.URL

val url = new java.net.URL("http://www.domain.com:8080/one/two")
val hostname = url.getHost // www.domain.com
val port = url.getPort     // 8080

A minor difference, getPort returns -1 if no port is specified, so you have to handle that case explicitly.

val port = if (url.getPort == -1) url.getDefaultPort else url.getPort

how to Extract hostname from url using jquery

To do that you can simply use the String.prototype.split() method with / as delimiter to extract the hostname and then you take the end of the hostname (that contains a dot) with String.prototype.match():

var m = url.split('/')[0].match(/[^.]+\.[^.]+$/);
if (m)
    var domain = m[0];

Note: if the url begins with a scheme you need to remove it before:

var pat = '^https?://';
url = url.replace(new RegExp(pat, 'i'), '');

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An other way consists to find the domain directly:

var pat = '^(?:https?://)?(?:[^/:]*:[^/@]*@)?[^/]*([^./]+\\.[^./]+)';
var m = url.match(new RegExp(pat, 'i'));
if (m)
    var domain = m[1];

But in this case, you need to deal with a possible login/pass part before the hostname. This is the reason of this subpattern: (?:[^/:]*:[^/@]*@)?

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