How to check if a variable contains a valid url using PHP and jQuery?

Question

I'm trying to make a whois check script.

User can submit some domain address and then get a message if it's available or not.

$_POST['url'] is the submitted value by user.

How do I know if this variable is a domain name address?

It should give true for domains like:

http://google.com
www.google.com
http://www.google.com
google.com

Same for javascript (I'm using ajax-validation also)?

possible duplicate of [Parsing Domain From URL In PHP](http://stackoverflow.com/questions/276516/parsing-domain-from-url-in-php) — Jon, Dec 21 '11 at 15:04
@Madmartigan I think we shouldn't send any queries since valid url is submitted — Jasper, Dec 21 '11 at 15:23
@Madmartigan True, but http://coca.cola isn't a valid URL (yet). — Tom van der Woerdt, Dec 21 '11 at 15:24
Anyone knows some similar script to check domain address by javascript or jQuery? — Jasper, Dec 21 '11 at 15:24
Sorry, deleted my comment too soon. For clarity to anyone else reading, it was "Doesn't the Whois check do the URL validation?". — Wesley Murch, Dec 21 '11 at 15:26
whois check is done on a third-party resource. I'm using jQuery to validate the url, if its true, send value to php, which checks the domain, then get value back from ajax and show the message to the user. — Jasper, Dec 21 '11 at 15:28
@Steve Maybe this will help you validate the url in jQuery: http://www.robsearles.com/2010/05/27/jquery-validate-url-adding-http/ — slinzerthegod, Dec 21 '11 at 15:37
You really should make the distinction between "valid url" and "valid domain name", they are two completely different things. — Wesley Murch, Dec 21 '11 at 15:39

score 6 · Accepted Answer · edited Dec 21 '11 at 15:33

6

If you want to check if the url is a valid url you could use filter_var() with the FILTER_VALIDATE_URL filter.

filter_var($_POST['url'], FILTER_VALIDATE_URL)

edited Dec 21 '11 at 15:33

Wesley Murch

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answered Dec 21 '11 at 15:15

slinzerthegod

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@Steve Easy fix, simply prepend http:// if there is none, then use this function. – Tom van der Woerdt Dec 21 '11 at 15:23
@Madmartigan ok, do you know some solution for javascript check? – Jasper Dec 21 '11 at 15:25
1

@Steve I'm sorry I missed your example urls. I thought that you wanted to check if the url was valid. An url without protocol is not an valid url. – slinzerthegod Dec 21 '11 at 15:29
@Steve: IMO, either enforce a strict URL format, either by validation or formatting the string yourself, then just pass it over to the Whois API. The thing is, you are trying to accept and validate strings that simply are not valid URLs by themselves, like `this.one`. – Wesley Murch Dec 21 '11 at 15:31

Lion King · Answer 2 · 2011-12-21T19:20:04.530

1

You can use the following code:

Example:

$url = "http://0gate.com"; // you can use instead - $_POST['url']
if (!preg_match("/^[http|https]*[:\/\/]*[A-Za-z0-9\-_]+\.([A-Za-z]{3,4})+([\.A-Za-z]{3})*$/i", $url)) {
  echo "The domain [not valid - false]";
}else{
  echo "The domain is [valid - true]";
}

edited Dec 21 '11 at 19:20

answered Dec 21 '11 at 15:10

Lion King

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Oh you mean like [this](http://stackoverflow.com/a/276525/398242)? If you are going to copy/paste answers, at least attribute your source. – Wesley Murch Dec 21 '11 at 15:11
If you only need the host you can use `$host = parse_url($url, PHP_URL_HOST);` – Grexis Dec 21 '11 at 15:13
2

@LionKing: No offense, it was just blatantly obvious that you copied the linked answer and changed a few characters. – Wesley Murch Dec 21 '11 at 15:16
@Lion King Helping correctly when a question is already answered would be linking to the question in a comment and/or flagging this question. – Repox Dec 21 '11 at 15:20
what, if its not a domain, how do we know? false on $getdomain? – Jasper Dec 21 '11 at 15:20
@Steve: The value will be NULL. Quoting the [docs](http://us.php.net/parse_url): `If the requested component doesn't exist within the given URL, NULL will be returned.` – Wesley Murch Dec 21 '11 at 15:22
Do not use this regex, it is wrong on so many levels. You do not know about ccTLDs for example? – Patrick Mevzek Jan 04 '18 at 15:13

How to check if a variable contains a valid url using PHP and jQuery?

2 Answers2