Linkify

Turn plain-text URLs into hyperlinks
// ==UserScript==

// @name		  Linkify
// @version        0.1
// @namespace	  http://youngpup.net/userscripts

// @description   Turn plain-text URLs into hyperlinks

// @include *

// ==/UserScript==



// based on code by Aaron Boodman

// and included here with his gracious permission



var urlRegex = /\b(https?:\/\/[^\s+\"\<\>]+)/ig;

var snapTextElements = document.evaluate("//text()[not(ancestor::a) " + 

                                         "and not(ancestor::script) and not(ancestor::style) and " + 

                                         "contains(translate(., 'HTTP', 'http'), 'http')]", 

                                         document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);

for (var i = snapTextElements.snapshotLength - 1; i >= 0; i--) {

    var elmText = snapTextElements.snapshotItem(i);

    if (urlRegex.test(elmText.nodeValue)) {

        var elmSpan = document.createElement("span");

        var sURLText = elmText.nodeValue;

        elmText.parentNode.replaceChild(elmSpan, elmText);

        urlRegex.lastIndex = 0;

        for (var match = null, lastLastIndex = 0;

             (match = urlRegex.exec(sURLText)); ) { 

            elmSpan.appendChild(document.createTextNode(

                sURLText.substring(lastLastIndex, match.index))); 

            var elmLink = document.createElement("a"); 

            elmLink.setAttribute("href", match[0]); 

            elmLink.appendChild(document.createTextNode(match[0])); 

            elmSpan.appendChild(elmLink); 

            lastLastIndex = urlRegex.lastIndex;

        }

        elmSpan.appendChild(document.createTextNode(

            sURLText.substring(lastLastIndex)));

        elmSpan.normalize();

    }

}