diff --git a/build.js b/build.js
index 4ae8c86..057dc77 100644
--- a/build.js
+++ b/build.js
@@ -2,13 +2,14 @@ import fs from 'node:fs'
 import {emojiEmotion} from 'emoji-emotion'
 import {emojiToName} from 'gemoji'
 
+/** @type {Record<string, number>} */
 const data = {}
 let index = -1
 
 while (++index < emojiEmotion.length) {
-  data[emojiEmotion[index].emoji] = emojiEmotion[index].polarity
-  data[':' + emojiToName[emojiEmotion[index].emoji] + ':'] =
-    emojiEmotion[index].polarity
+  const info = emojiEmotion[index]
+  data[info.emoji] = info.polarity
+  data[':' + emojiToName[info.emoji] + ':'] = info.polarity
 }
 
 fs.writeFileSync(
diff --git a/index.js b/index.js
index a01eff1..6ffa8fc 100644
--- a/index.js
+++ b/index.js
@@ -83,7 +83,7 @@ export function inject(values) {
  * Get the polarity of a word.
  *
  * @param {string} value
- * @param {Inject} inject
+ * @param {Inject} [inject]
  * @returns {number}
  */
 function getPolarity(value, inject) {
diff --git a/test/index.js b/test/index.js
index 9d34f30..1cb5219 100644
--- a/test/index.js
+++ b/test/index.js
@@ -158,7 +158,13 @@ test('algorithm', function (t) {
   t.end()
 })
 
-// Simple word tokenizer.
+/**
+ * Simple word tokenizer.
+ *
+ * @param {string} value
+ * @returns {Array<string>}
+ */
 function tokenize(value) {
-  return value.toLowerCase().match(/\S+/g)
+  const match = value.toLowerCase().match(/\S+/g)
+  return match ? [...match] : []
 }
diff --git a/tsconfig.json b/tsconfig.json
index be08abe..016d1f4 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,15 +1,17 @@
 {
-  "include": ["*.js"],
+  "include": ["**/**.js"],
+  "exclude": ["coverage", "node_modules"],
   "compilerOptions": {
-    "target": "ES2020",
-    "lib": ["ES2020"],
-    "module": "ES2020",
-    "moduleResolution": "node",
-    "allowJs": true,
     "checkJs": true,
     "declaration": true,
     "emitDeclarationOnly": true,
-    "allowSyntheticDefaultImports": true,
-    "skipLibCheck": true
+    "exactOptionalPropertyTypes": true,
+    "forceConsistentCasingInFileNames": true,
+    "lib": ["es2020"],
+    "module": "node16",
+    "newLine": "lf",
+    "skipLibCheck": true,
+    "strict": true,
+    "target": "es2020"
   }
 }