PHP: Detect if string is a hyperlink and make it clickable

Question

In most chat applications when a user inputs a hyperlink, it automatically becomes clickable in the chat window. How do I replicate this behavior using PHP/JavaScript/JQuery?

Essentially my idea of making it work is testing the chat message string for hyperlinks and encasing them in <a href> tags with themselves as the link. Is that correct, and if so, how do I do it? Also, how would I make it so that the links open in a new tab, instead of replacing my page?

EDIT This took me quite a bit of trial and error, but this PHP function should work in all realistic scenarios:

function formatTextLinks($text) {
    $words = preg_split("/[\s,]+/", $text);
    $offset = 0;

    foreach($words as $value) {
        preg_match("/^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/", $value, $matches);

        $s = $matches[0];
        if(!is_string($s)) continue;
        $pos = strpos($text, $s, $offset);
        if($pos !== false) {
            $helper = "";
            if(strpos($s, "http://") === false || strpos($s, "https://") === false) $helper = "http://";
            $text = substr_replace($text, "<a href='".$helper.$s."' target='_blank'>".$s."</a>", $pos, strlen($s));
            $offset = $pos + strlen("<a href='".$helper.$s."' target='_blank'>".$s."</a>");
        }
    }

    return $text;
}

@RiggsFolly How would I rephrase it? It seems straightforward to me; all I'm asking is how could I detect that a string contains a url (fully-qualified or not, it just needs to work in an address bar) and then make it clickable as a hyperlink. — StrongJoshua
– StrongJoshua, Commented Sep 30, 2014 at 3:00
fully-qualified: regex for http://. Or not: Unless you have a regex for .com|.org|.net|ect, probably isnt feasable — Oberst
– Oberst, Commented Sep 30, 2014 at 3:02
I would have the PHP generating the page create the applicable anchor when it sends out the data. The chat application does this the same way: after the user enters input it applies a heuristic to guess if it's a URL, if it looks like a URL it treats it like a URL (same way with smiley-faces and whatnot). The actual heuristic may be "loose" such as only looking for valid_public_domain/valid_path (e.g. not needing protocol portion) or "strict" in requiring a full valid URL with protocol. — user2864740
– user2864740, Commented Sep 30, 2014 at 3:09

IgorAlves · Accepted Answer · 2014-09-30 03:04:40Z

2

You could use a php or javascript regular expression to test if it is a URL (link). If yes create a html link tag using jquery.

This is the regex pattern

/^(https?:\/\/)?([\da-z\.-]+)\.([a-z\.]{2,6})([\/\w \.-]*)*\/?$/

This is the source http://code.tutsplus.com/tutorials/8-regular-expressions-you-should-know--net-6149

answered Sep 30, 2014 at 3:04

IgorAlves

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StrongJoshua Over a year ago

It was difficult figuring out a function to correctly format the text when it found the matches, especially because using preg_match_all using that regex returns matches that aren't hyperlinks at all, just parts of them (i.e. just the "http://" or the "www"). I'll post my working function into my question for any future visitors.

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