create direct links to x-posted subs

xpost.user.js

// ==UserScript==
// @name        reddit x-post
// @namespace   reddit_xpost
// @description add x-post link
// @include     https://www.reddit.com/*
// @version     1.1
// @grant       none
// ==/UserScript==

function makeXpostLinks () {

	var 
	titles        = document.querySelectorAll("a.title"),
	xpost_re      = /x-?post/i,
	xpost_from_re = /(x-?post\w*\b)(\s{0,1}\S+)?\s([r/]+)([a-zA-Z0-9]+)/i,
	debug         = 0;
	
	for (var i = 0, title, tagline, entry, userattrs, textNode, subreddit, add_after, xpost_from, xpost_from_a, sub; i < titles.length; i++) {

		title = titles[i];
		
		if ( xpost_re.test(title.innerHTML) && !title.classList.contains("x-post") ){

			xpost_from = title.innerHTML.match(xpost_from_re);

			if ( xpost_from && xpost_from.length >= 5 ){

				sub = xpost_from[4];
				entry = title.parentNode.parentNode;

				if ( entry && entry.classList.contains("entry") ){

					textNode = document.createTextNode(" x-posted from ");

					xpost_from_a           = document.createElement("a");
					xpost_from_a.href      = "https://www.reddit.com/r/"+sub;
					xpost_from_a.className = "subreddit hover";
					xpost_from_a.innerHTML = "/r/"+sub;

					userattrs = entry.querySelector(".userattrs");
					subreddit = entry.querySelector(".subreddit");
					tagline   = entry.querySelector(".tagline");

					add_after = subreddit || userattrs || tagline && tagline.lastChild;

					if ( add_after ){
						if ( add_after.nextSibling ){
							add_after.parentNode.insertBefore(textNode, add_after.nextSibling);
							add_after.parentNode.insertBefore(xpost_from_a, textNode.nextSibling);
						} else {
							add_after.parentNode.appendChild(textNode);
							add_after.parentNode.appendChild(xpost_from_a);
						}
					} else {
						if (debug) console.error("add_after is null");
					}
					title.classList.add("x-post");
				} else {
					if (debug) console.error("entry is null");
				}
			} 
		}
	}
}
document.addEventListener("DOMContentLoaded", makeXpostLinks);
window.addEventListener("neverEndingLoad", makeXpostLinks);