_mb. RANDOM RG for cats.user.js

// ==UserScript==
// @name         mb. RANDOM RG for cats
// @version      2013.0605.1111
// @description  musicbrainz.org: provides a random release group link from an artist page
// @namespace    https://gist.github.com/jesus2099/5697130
// @author       Tristan DANIEL (PATATE12 aka. jesus2099/shamo)
// @licence      CC BY-NC-SA 3.0 FR (http://creativecommons.org/licenses/by-nc-sa/3.0/fr/)
// @requester    ZaphodBeeblebrox
// @since        2013.6.3.
// @grant        none
// @match        *://*.musicbrainz.org/artist/*
// @run-at       document-end
// ==/UserScript==
if(self.location.href.match(/^https?:\/\/([^.]+\.)?musicbrainz\.org\/artist\/.+$/)){/*@matchopera*/(function(){"use strict";
	var RE_GUID = "[a-f0-9]{8}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{4}-[a-f0-9]{12}";
	var MBS = self.location.protocol+"//"+self.location.host;
	var art = document.querySelector("div.artistheader h1 a[href^='"+MBS+"/artist/']");
	var tgt = document.querySelector("div.artistheader p.subheader");
	var mbid;
	if (art && tgt && (mbid = art.getAttribute("href").match(new RegExp("/artist/("+RE_GUID+")$")))) {
		randomRG();
	}
	function randomRG() {
		var xhr = new XMLHttpRequest();
		xhr.addEventListener("load", function(e) {
			var artist = JSON.parse(this.responseText);
			var rg = artist["release-group"][Math.floor(Math.random()*artist["release-group"].length)];
			var cont = tgt.appendChild(createTag("span", null, [
				" 〜 ",
				createTag("a", {"a":{"title":"re-randomize among "+artist["release-group"].length+" release groups"},"e":{"click":function(e){
					del(getParent(this, "span"));
					randomRG();
				}}}, "Random"),
				" release-group: ",
				createTag("a", {"a":{"href":"/release-group/"+rg.id}}, [
					createTag("img", {"a":{"src":"//coverartarchive.org/release-group/"+rg.id+"/front-250","alt":"♥"},"s":{"display":"none","vertical-align":"text-top","max-height":self.getComputedStyle(tgt).getPropertyValue("height")},"e":{"load":function(e){del(this.style.setProperty("display","inline"));}}}),
					" "+rg.title
				])
			]));
			if (rg.disambiguation.length > 0) {
				cont.appendChild(document.createTextNode(" ("+rg.disambiguation+")"));
			}
		}, false);
		xhr.open("get", "/ws/2/release-group?query=arid:"+mbid[1]+"&limit=100&fmt=json");
		xhr.send(null);
	}
	function createTag(tag, gadgets, children) {
		var t = document.createElement(tag);
		if(t.tagName) {
			if (gadgets) {
				for (var attri in gadgets.a) { if (gadgets.a.hasOwnProperty(attri)) { t.setAttribute(attri, gadgets.a[attri]); } }
				for (var style in gadgets.s) { if (gadgets.s.hasOwnProperty(style)) { t.style.setProperty(style.replace(/!/,""), gadgets.s[style], style.match(/!/)?"important":""); } }
				for (var event in gadgets.e) { if (gadgets.e.hasOwnProperty(event)) { t.addEventListener(event, gadgets.e[event], false); } }
			}
			if (t.tagName == "A" && !t.getAttribute("href") && !t.style.getPropertyValue("cursor")) { t.style.setProperty("cursor", "pointer"); }
			if (children) { var chldrn = children; if (typeof chldrn == "string" || chldrn.tagName) { chldrn = [chldrn]; } for(var child=0; child<chldrn.length; child++) { t.appendChild(typeof chldrn[child]=="string"?document.createTextNode(chldrn[child]):chldrn[child]); } t.normalize(); }
		}
		return t;
	}
	function del(o) {
		return o.parentNode.removeChild(o);
	}
	function getParent(obj, tag, cls) {
		var cur = obj;
		if (cur.parentNode) {
			cur = cur.parentNode;
			if (cur.tagName.toUpperCase() == tag.toUpperCase() && (!cls || cls && cur.className.match(new RegExp("\\W*"+cls+"\\W*")))) {
				return cur;
			} else {
				return getParent(cur, tag, cls);
			}
		} else {
			return null;
		}
	}
})();}