1 files changed, 32 insertions, 0 deletions
diff --git a/app/assets/javascripts/milestones/milestone_utils.js b/app/assets/javascripts/milestones/milestone_utils.js
new file mode 100644
index 00000000000..3ae5e676138
--- /dev/null
+++ b/app/assets/javascripts/milestones/milestone_utils.js
@@ -0,0 +1,32 @@
+import { parsePikadayDate } from '~/lib/utils/datetime_utility';
+
+/**
+ * This method is to be used with `Array.prototype.sort` function
+ * where array contains milestones with `due_date`/`dueDate` and/or
+ * `expired` properties.
+ * This method sorts given milestone params based on their expiration
+ * status by putting expired milestones at the bottom and upcoming
+ * milestones at the top of the list.
+ *
+ * @param {object} milestoneA
+ * @param {object} milestoneB
+ */
+export function sortMilestonesByDueDate(milestoneA, milestoneB) {
+  const rawDueDateA = milestoneA.due_date || milestoneA.dueDate;
+  const rawDueDateB = milestoneB.due_date || milestoneB.dueDate;
+  const dueDateA = rawDueDateA ? parsePikadayDate(rawDueDateA) : null;
+  const dueDateB = rawDueDateB ? parsePikadayDate(rawDueDateB) : null;
+  const expiredA = milestoneA.expired || Date.now() > dueDateA?.getTime();
+  const expiredB = milestoneB.expired || Date.now() > dueDateB?.getTime();
+
+  // Move all expired milestones to the bottom.
+  if (expiredA) return 1;
+  if (expiredB) return -1;
+
+  // Move milestones without due dates just above expired milestones.
+  if (!dueDateA) return 1;
+  if (!dueDateB) return -1;
+
+  // Sort by due date in ascending order.
+  return dueDateA - dueDateB;
+}