infra(unicorn): no-array-reduce (#2479)

1 files changed, 25 insertions, 0 deletions

diff --git a/src/internal/group-by.ts b/src/internal/group-by.ts
new file mode 100644
index 00000000..ff3242c9
--- /dev/null
+++ b/src/internal/group-by.ts
@@ -0,0 +1,25 @@
+/**
+ * Groups the values by the key function.
+ *
+ * @internal
+ *
+ * @param values The values to group.
+ * @param keyFunction The function to get the key from the value.
+ */
+export function groupBy<TValue>(
+  values: ReadonlyArray<TValue>,
+  keyFunction: (value: TValue) => string | number
+): Record<string, TValue[]> {
+  const result: Record<string, TValue[]> = {};
+
+  for (const value of values) {
+    const key = keyFunction(value);
+    if (result[key] === undefined) {
+      result[key] = [];
+    }
+
+    result[key].push(value);
+  }
+
+  return result;
+}