[Python-checkins] [2.7] bpo-24712: Doc: Make sidebar sticky using browser support. (GH-13179)

[Stéphane Wirtel]

https://github.com/python/cpython/commit/8ab24b2ebcf99f703f00297cb3a0c3ff857eecf8
commit: 8ab24b2ebcf99f703f00297cb3a0c3ff857eecf8
branch: 2.7
author: Julien Palard <julien at palard.fr>
committer: Stéphane Wirtel <stephane at wirtel.be>
date: 2019-05-08T09:32:07-04:00
summary:

[2.7] bpo-24712: Doc: Make sidebar sticky using browser support. (GH-13179)

Patch by Mike Taylor.

files:
M Doc/tools/static/sidebar.js

diff --git a/Doc/tools/static/sidebar.js b/Doc/tools/static/sidebar.js
index 1bdd829a7683..17f818ec140e 100644
--- a/Doc/tools/static/sidebar.js
+++ b/Doc/tools/static/sidebar.js
@@ -46,6 +46,15 @@ $(function() {
   var dark_color = $('.related').css('background-color');
   var light_color = $('.document').css('background-color');
 
+  // set position: sticky on sidebar
+  // (browsers that don't support this will fall-back to
+  // positioning via scroll_sidebar)
+  var supportsPositionSticky = (window.CSS && window.CSS.supports &&
+                                window.CSS.supports('position', 'sticky'));
+  if (supportsPositionSticky) {
+    sidebarwrapper.css('position', 'sticky');
+  }
+
   function get_viewport_height() {
     if (window.innerHeight)
       return window.innerHeight;
@@ -157,6 +166,9 @@ $(function() {
 
   /* intelligent scrolling */
   function scroll_sidebar() {
+    if (supportsPositionSticky) {
+      return;
+    }
     var sidebar_height = sidebarwrapper.height();
     var viewport_height = get_viewport_height();
     var offset = sidebar.position()['top'];