Refactoring to allow for a more flexible API.

docs/playpen.js

@@ -0,0 +1,43 @@
+// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+/*jslint browser: true, es5: true */
+/*globals $: true, rootPath: true */
+
+document.addEventListener('DOMContentLoaded', function() {
+    'use strict';
+
+    if (!window.playgroundUrl) {
+        return;
+    }
+
+    var featureRegexp = new RegExp('^\s*#!\\[feature\\(\.*?\\)\\]');
+    var elements = document.querySelectorAll('pre.rust-example-rendered');
+
+    Array.prototype.forEach.call(elements, function(el) {
+        el.onmouseover = function(e) {
+            if (el.contains(e.relatedTarget)) {
+                return;
+            }
+
+            var a = el.querySelectorAll('a.test-arrow')[0];
+
+            var code = el.previousElementSibling.textContent;
+
+            var channel = '';
+            if (featureRegexp.test(code)) {
+                channel = '&version=nightly';
+            }
+
+            a.setAttribute('href', window.playgroundUrl + '?code=' +
+                           encodeURIComponent(code) + channel);
+        };
+    });
+});