Backport search from v4 and adapt it for v3.4.0.

docs/assets/js/src/search.js

@@ -0,0 +1,51 @@
+// NOTICE!! DO NOT USE ANY OF THIS JAVASCRIPT
+// IT'S ALL JUST JUNK FOR OUR DOCS!
+// ++++++++++++++++++++++++++++++++++++++++++
+
+(function () {
+  'use strict'
+
+  var inputElement = document.getElementById('search-input')
+
+  if (!window.docsearch || !inputElement) {
+    return
+  }
+
+  function getOrigin() {
+    var location = window.location
+    var origin = location.origin
+
+    if (!origin) {
+      var port = location.port ? ':' + location.port : ''
+
+      origin = location.protocol + '//' + location.hostname + port
+    }
+
+    return origin
+  }
+
+  window.docsearch({
+    apiKey: 'c8948afa20e6437a6e829f7e87b9ac11',
+    indexName: 'bootstrap-v3',
+    inputSelector: '#search-input',
+    handleSelected: function (input, event, suggestion) {
+      var url = suggestion.url
+      url = suggestion.isLvl1 ? url.split('#')[0] : url
+      // If it's a title we remove the anchor so it does not jump.
+      window.location.href = url
+    },
+    transformData: function (hits) {
+      return hits.map(function (hit) {
+        var siteurl = getOrigin()
+        var urlRE = /^https?:\/\/getbootstrap\.com/
+
+        // When in production, return the result as is,
+        // otherwise remove our url from it.
+        hit.url = siteurl.match(urlRE) ? hit.url : hit.url.replace(urlRE, '')
+
+        return hit
+      })
+    },
+    debug: false // Set debug to true if you want to inspect the dropdown
+  })
+}())