Change file to TS

Author: LekoArts

packages/custom-properties/package.json

@@ -16,6 +16,7 @@
     "access": "public"
   },
   "dependencies": {
+    "@theme-ui/core": "^0.3.1",
     "pluralize": "^8.0.0"
   },
   "devDependencies": {

packages/custom-properties/src/index.ts

@@ -1,9 +1,14 @@
 import pluralize from 'pluralize'
+import { Theme } from '@theme-ui/core/dist/theme'
 
-export default (theme, prefix) => {
-  const customProperties = {}
+interface CustomProperties {
+  [key: string]: string | number
+}
+
+export default (theme: Theme, prefix?: string) => {
+  const customProperties: CustomProperties = {}
 
-  const generateProperties = (object, previousKey) => {
+  const generateProperties = (object: object, previousKey?: string) => {
     Object.entries(object).forEach(([key, value]) => {
       let formattedKey = pluralize(key, 1)