diff --git a/.eslintrc.js b/.eslintrc.js
index 609dafb34..83e8a79ad 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -16,7 +16,7 @@ const javascriptSettings = {
 const typescriptSettings = {
   files: ['*.ts', '*.mts'],
   parserOptions: {
-    project: './tsconfig.json'
+    project: './tsconfig.base.json'
   },
   plugins: [
     '@typescript-eslint'
diff --git a/jsconfig.json b/jsconfig.json
new file mode 100644
index 000000000..7f5b3fad9
--- /dev/null
+++ b/jsconfig.json
@@ -0,0 +1,14 @@
+{
+  "extends": "./tsconfig.base",
+  "compilerOptions": {
+    "allowJs": true,
+    "checkJs": true,
+    "noImplicitAny": false,
+    "noImplicitThis": false
+  },
+  "include": [
+    "**/*.ts",
+    "index.js",
+    "lib/**/*.js"
+  ]
+}
diff --git a/lib/suggestSimilar.js b/lib/suggestSimilar.js
index 9a4066c71..75a527700 100644
--- a/lib/suggestSimilar.js
+++ b/lib/suggestSimilar.js
@@ -1,3 +1,5 @@
+// @ts-check
+
 const maxDistance = 3;
 
 function editDistance(a, b) {
diff --git a/package.json b/package.json
index 0d7168fc2..2bbd105d6 100644
--- a/package.json
+++ b/package.json
@@ -25,7 +25,7 @@
     "test": "jest && npm run test-typings",
     "test-esm": "node ./tests/esm-imports-test.mjs",
     "test-typings": "tsd",
-    "typescript-checkJS": "tsc --allowJS --checkJS index.js lib/*.js --noEmit",
+    "typescript-checkJs": "tsc -p jsconfig.json",
     "test-all": "npm run test && npm run lint && npm run typescript-checkJS && npm run test-esm"
   },
   "files": [
diff --git a/tsconfig.base.json b/tsconfig.base.json
new file mode 100644
index 000000000..59aa560f3
--- /dev/null
+++ b/tsconfig.base.json
@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "module": "commonjs",
+    "lib": [
+      "es6"
+    ],
+    "noImplicitAny": true,
+    "noImplicitThis": true,
+    "strictNullChecks": true,
+    "types": [
+      "node",
+      "jest"
+    ],
+    "noEmit": true,
+    "forceConsistentCasingInFileNames": true
+  },
+  "include": [
+    "**/*.ts"
+  ]
+}
diff --git a/tsconfig.json b/tsconfig.json
deleted file mode 100644
index d2688174b..000000000
--- a/tsconfig.json
+++ /dev/null
@@ -1,18 +0,0 @@
-{
-    "compilerOptions": {
-        "module": "commonjs",
-        "lib": [
-            "es6"
-        ],
-        "noImplicitAny": true,
-        "noImplicitThis": true,
-        "strictNullChecks": true,
-        "types": [
-          "node",
-          "jest"
-        ],
-        "noEmit": true,
-        "forceConsistentCasingInFileNames": true
-    },
-    "include": ["**/*.ts"],
-}