Add mkdocs search hack.

Should close #3376.

Copy-Pasta from nodemcu/nodemcu-firmware@7dd89dd.

ChangeLog.md

@@ -122,6 +122,10 @@ Bug fixes:
   trust the etag and not re-download.  Fixed in this version.
 * Invoking `stack --docker` in parallel now correctly locks the sqlite database.
   See [#3400](https://github.com/commercialhaskell/stack/issues/3400).
+* docs.haskellstack.org RTD documentation search is replaced by the mkdocs
+  search. Please see
+  [#3376](https://github.com/commercialhaskell/stack/issues/3376).
+
 
 ## 1.5.1
 

etc/mkdocsjs/searchhack.js

@@ -0,0 +1,29 @@
+// Please see https://github.com/commercialhaskell/stack/issues/3376
+
+(function () {
+  $(document).ready(function () {
+    fixSearch();
+  });
+
+  function fixSearch() {
+    var target = document.getElementById('rtd-search-form');
+    var config = {attributes: true, childList: true};
+
+    var observer = new MutationObserver(function(mutations) {
+      observer.disconnect();
+      var form = $('#rtd-search-form');
+      form.empty();
+      form.attr('action', 'https://' + window.location.hostname + '/en/' + determineSelectedBranch() + '/search.html');
+      $('<input>').attr({
+        type: "text",
+        name: "q",
+        placeholder: "Search docs"
+      }).appendTo(form);
+    });
+
+    if (window.location.origin.indexOf('readthedocs') > -1) {
+      observer.observe(target, config);
+    }
+  }
+
+})();

mkdocs.yml

@@ -38,3 +38,6 @@ pages:
 markdown_extensions:
 - toc:
     permalink: true
+
+extra_javascript:
+- etc/mkdocsjs/searchhack.js