fix: make arrays readonly (#154)

* fix: make arrays readonly

* fix: make arrays readonly

.nvmrc

@@ -1 +1 @@
-18.19.0
+20.11.1

package.json

@@ -24,7 +24,7 @@
     "src"
   ],
   "scripts": {
-    "build": "scripty",
+    "build": "npm run clean && npx tsc && npx rollup -c",
     "clean": "scripty",
     "commit": "scripty",
     "commit:protect": "scripty",

scripts/build/index.sh

@@ -3,4 +3,4 @@
 
 npm run clean
 echo "┏━━━ 📦 build ━━━━━━━━━━━━━━━━━━━"
-tsc && rollup -c
+npx tsc && npx rollup -c

src/typings/types.ts

@@ -1,6 +1,11 @@
 export type ObjectKey = string | number | symbol;
 
 export type EntityDict<Entity, Key extends ObjectKey> = {
+  entities: Record<Key, ReadonlyArray<Entity> | undefined>;
+  ids: ReadonlyArray<Key>;
+};
+
+export type MutableEntityDict<Entity, Key extends ObjectKey> = {
   entities: Record<Key, Entity[] | undefined>;
   ids: Key[];
 };

src/utils/__internal__/groupBy.ts

@@ -1,4 +1,4 @@
-import type { EntityDict } from '../../typings';
+import type { MutableEntityDict } from '../../typings';
 
 /**
  * O(n) implementation of groupBy
@@ -7,7 +7,7 @@ export const groupBy = <K extends keyof T, T extends Record<K, T[K]>>(
   key: K,
   items: T[]
 ) => {
-  const result = { entities: {}, ids: [] } as EntityDict<T, T[K]>;
+  const result = { entities: {}, ids: [] } as MutableEntityDict<T, T[K]>;
 
   for (let i = 0; i < items.length; i++) {
     if (result.entities[items[i][key]]) {