From 89ca858bb57e411bebd0083e4a76b8f70e6fa9aa Mon Sep 17 00:00:00 2001
From: Pascal Hertleif <killercup@gmail.com>
Date: Sat, 10 Jan 2015 11:55:48 +0100
Subject: [PATCH] Fix `playpen.js` errors on `pre`s without IDs

This adds an early return to skip code blocks without IDs.

Fixes #20864.
---
 src/librustdoc/html/static/playpen.js | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/librustdoc/html/static/playpen.js b/src/librustdoc/html/static/playpen.js
index 473a20086edb1..f7d6b872940a4 100644
--- a/src/librustdoc/html/static/playpen.js
+++ b/src/librustdoc/html/static/playpen.js
@@ -14,6 +14,7 @@
 (function() {
     if (window.playgroundUrl) {
         $('pre.rust').hover(function() {
+            if (!$(this).attr('id')) { return; }
             var id = '#' + $(this).attr('id').replace('rendered', 'raw');
             var a = $('<a>').text('⇱').attr('class', 'test-arrow');
             var code = $(id).text();