How to Replace Plain Urls With Links

How to replace plain URLs with links?

First off, rolling your own regexp to parse URLs is a terrible idea. You must imagine this is a common enough problem that someone has written, debugged and tested a library for it, according to the RFCs. URIs are complex - check out the code for URL parsing in Node.js and the Wikipedia page on URI schemes.

There are a ton of edge cases when it comes to parsing URLs: international domain names, actual (.museum) vs. nonexistent (.etc) TLDs, weird punctuation including parentheses, punctuation at the end of the URL, IPV6 hostnames etc.

I've looked at a ton of libraries, and there are a few worth using despite some downsides:

Soapbox's linkify has seen some serious effort put into it, and a major refactor in June 2015 removed the jQuery dependency. It still has issues with IDNs.
AnchorMe is a newcomer that claims to be faster and leaner. Some IDN issues as well.
Autolinker.js lists features very specifically (e.g. "Will properly handle HTML input. The utility will not change the href attribute inside anchor () tags"). I'll thrown some tests at it when a demo becomes available.

Libraries that I've disqualified quickly for this task:

Django's urlize didn't handle certain TLDs properly (here is the official list of valid TLDs. No demo.
autolink-js wouldn't detect "www.google.com" without http://, so it's not quite suitable for autolinking "casual URLs" (without a scheme/protocol) found in plain text.
Ben Alman's linkify hasn't been maintained since 2009.

If you insist on a regular expression, the most comprehensive is the URL regexp from Component, though it will falsely detect some non-existent two-letter TLDs by looking at it.

How to replace plain URLs with links, with example?

Over at CodeReview this question was answered quite splendidly.

function replaceURLWithHTMLLinks(text) {
    var re = /(\(.*?)?\b((?:https?|ftp|file):\/\/[-a-z0-9+&@#\/%?=~_()|!:,.;]*[-a-z0-9+&@#\/%=~_()|])/ig;
    return text.replace(re, function(match, lParens, url) {
        var rParens = '';
        lParens = lParens || '';

        // Try to strip the same number of right parens from url
        // as there are left parens.  Here, lParenCounter must be
        // a RegExp object.  You cannot use a literal
        //     while (/\(/g.exec(lParens)) { ... }
        // because an object is needed to store the lastIndex state.
        var lParenCounter = /\(/g;
        while (lParenCounter.exec(lParens)) {
            var m;
            // We want m[1] to be greedy, unless a period precedes the
            // right parenthesis.  These tests cannot be simplified as
            //     /(.*)(\.?\).*)/.exec(url)
            // because if (.*) is greedy then \.? never gets a chance.
            if (m = /(.*)(\.\).*)/.exec(url) ||
                    /(.*)(\).*)/.exec(url)) {
                url = m[1];
                rParens = m[2] + rParens;
            }
        }
        return lParens + "<a href='" + url + "'>" + url + "</a>" + rParens;
    });
}

Note: I had errors with the "@" symbol in the "var re" - I just replaced it with @@

How to replace plain text URLs with links and hashtags in PHP

Your regex for hashtag is this:

/[#]+([A-Za-z0-9-_]+)/

Your stated goal is to make sure it's not part of a URL, which you identify by:

/https?\:\/\//

You can try to use a negative look-behind:

/(?<!https?\:\/\/)[^#]*[#]+([A-Za-z0-9-_]+)

This is not enough for all general cases, but it sounds like you're trying to solve a problem within a scope under your control (a text file you own or something) so hopefully this well help you.

Replace all URLs in text to clickable links in PHP

function convert($input) {
   $pattern = '@(http(s)?://)?(([a-zA-Z])([-\w]+\.)+([^\s\.]+[^\s]*)+[^,.\s])@';
   return $output = preg_replace($pattern, '<a href="http$2://$3">$0</a>', $input);
}

demo

Replace plain URL with link if domain matches

You could use regex to replace and then append.

var str = "Hey this is a link to somesite.co bye bye";
str = str.replace(/(somesite\.co)/g, "<a href="$1">$1</a>");
var a = document.createElement('a');
a.outerHTML = str;
document.body.appendChild(a);