Added groupBy

src/groupBy.ts

@@ -0,0 +1,20 @@
+import { curry } from './curry';
+import { Obj } from './types';
+
+interface GroupByFn {
+  <T = unknown>(fn: (a: T) => unknown): (arr: T[]) => Obj<T[]>;
+  <T = unknown>(fn: (a: T) => unknown, arr: T[]): Obj<T[]>;
+}
+
+/**
+ * TODO: adicionar documentação
+ */
+export const groupBy = curry((fn: Function, items: unknown[]) => {
+  const res = {} as Obj;
+  for (const item of items) {
+    const key = fn(item);
+    res[key] ||= [];
+    res[key].push(item);
+  }
+  return res;
+}) as GroupByFn;

src/index.ts

@@ -22,6 +22,7 @@ export * from './flow';
 export * from './formatCurrency';
 export * from './formatPhone';
 export * from './get';
+export * from './groupBy';
 export * from './groupByEveryN';
 export * from './includes';
 export * from './isArray';