1 files changed, 17 insertions, 3 deletions
diff --git a/app/assets/javascripts/diffs/store/getters_versions_dropdowns.js b/app/assets/javascripts/diffs/store/getters_versions_dropdowns.js
index 14c51602f28..dd682060b4b 100644
--- a/app/assets/javascripts/diffs/store/getters_versions_dropdowns.js
+++ b/app/assets/javascripts/diffs/store/getters_versions_dropdowns.js
@@ -1,5 +1,6 @@
 import { __, n__, sprintf } from '~/locale';
-import { DIFF_COMPARE_BASE_VERSION_INDEX } from '../constants';
+import { getParameterByName, parseBoolean } from '~/lib/utils/common_utils';
+import { DIFF_COMPARE_BASE_VERSION_INDEX, DIFF_COMPARE_HEAD_VERSION_INDEX } from '../constants';
 
 export const selectedTargetIndex = state =>
   state.startVersion?.version_index || DIFF_COMPARE_BASE_VERSION_INDEX;
@@ -9,12 +10,25 @@ export const selectedSourceIndex = state => state.mergeRequestDiff.version_index
 export const diffCompareDropdownTargetVersions = (state, getters) => {
   // startVersion only exists if the user has selected a version other
   // than "base" so if startVersion is null then base must be selected
+
+  const diffHead = parseBoolean(getParameterByName('diff_head'));
+  const isBaseSelected = !state.startVersion && !diffHead;
+  const isHeadSelected = !state.startVersion && diffHead;
+
   const baseVersion = {
     versionName: state.targetBranchName,
     version_index: DIFF_COMPARE_BASE_VERSION_INDEX,
     href: state.mergeRequestDiff.base_version_path,
     isBase: true,
-    selected: !state.startVersion,
+    selected: isBaseSelected,
+  };
+
+  const headVersion = {
+    versionName: state.targetBranchName,
+    version_index: DIFF_COMPARE_HEAD_VERSION_INDEX,
+    href: state.mergeRequestDiff.head_version_path,
+    isHead: true,
+    selected: isHeadSelected,
   };
   // Appended properties here are to make the compare_dropdown_layout easier to reason about
   const formatVersion = v => {
@@ -25,7 +39,7 @@ export const diffCompareDropdownTargetVersions = (state, getters) => {
       ...v,
     };
   };
-  return [...state.mergeRequestDiffs.slice(1).map(formatVersion), baseVersion];
+  return [...state.mergeRequestDiffs.slice(1).map(formatVersion), baseVersion, headVersion];
 };
 
 export const diffCompareDropdownSourceVersions = (state, getters) => {