[memoize] Migrate to TypeScript

.changeset/hip-moons-play.md

@@ -0,0 +1,5 @@
+---
+'@emotion/memoize': minor
+---
+
+Migrate to TypeScript and emit declarations based on the code

jest.config.js

@@ -1,7 +1,7 @@
 module.exports = {
   transform: {
     '\\.css$': '<rootDir>/test/styleTransform.js',
-    '^.+\\.js?$': 'babel-jest'
+    '^.+\\.(tsx|ts|js)?$': 'babel-jest'
   },
   watchPlugins: [
     'jest-watch-typeahead/filename',

packages/memoize/package.json

@@ -4,7 +4,7 @@
   "description": "emotion's memoize utility",
   "main": "dist/emotion-memoize.cjs.js",
   "module": "dist/emotion-memoize.esm.js",
-  "types": "types/index.d.ts",
+  "types": "dist/declarations/src/index.d.ts",
   "license": "MIT",
   "repository": "https://github.com/emotion-js/emotion/tree/main/packages/memoize",
   "scripts": {

packages/memoize/src/index.ts

@@ -0,0 +1,8 @@
+export default function memoize<V>(fn: (arg: string) => V): (arg: string) => V {
+  const cache: Record<string, V> = Object.create(null)
+
+  return (arg: string) => {
+    if (cache[arg] === undefined) cache[arg] = fn(arg)
+    return cache[arg]
+  }
+}

packages/memoize/types/index.d.ts

@@ -1,3 +1 @@
-type Fn<T> = (key: string) => T
-
-export default function memoize<T>(fn: Fn<T>): Fn<T>
+export { default } from '../src'

packages/memoize/types/tests.ts

@@ -1,4 +1,4 @@
-import memoize from '@emotion/memoize'
+import memoize from '../src'
 
 // $ExpectType string[]
 memoize((arg: string) => [arg])('foo')

packages/memoize/types/tslint.json

@@ -18,6 +18,7 @@
     ],
 
     "no-unnecessary-generics": false,
-    "strict-export-declare-modifiers": false
+    "strict-export-declare-modifiers": false,
+    "no-default-import": false
   }
 }