fix .d.ts and add a basic typechecking example/CI

Author: tdumitrescu

.github/workflows/tests.yml

@@ -23,3 +23,4 @@ jobs:
         node-version: ${{ matrix.node-version }}
     - run: npm ci
     - run: npm test -- run --coverage
+    - run: npx tsc

lib/mixpanel-node.d.ts

@@ -162,11 +162,6 @@ declare namespace mixpanel {
     delete_group(groupKey: string, groupId: string, modifiers?: Modifiers, callback?: Callback): void;
     delete_group(groupKey: string, groupId: string, callback: Callback): void;
   }
-
-  // Export feature flags types for convenience
-  export { LocalFlagsConfig, RemoteFlagsConfig, FlagContext, SelectedVariant } from './flags/types';
-  export { default as LocalFeatureFlagsProvider } from './flags/local_flags';
-  export { default as RemoteFeatureFlagsProvider } from './flags/remote_flags';
 }
 
 export = mixpanel;

package-lock.json

@@ -27,9 +27,11 @@
   },
   "types": "./lib/mixpanel-node.d.ts",
   "devDependencies": {
+    "@types/node": "^24.10.1",
     "@vitest/coverage-v8": "^4.0.8",
     "nock": "^14.0.10",
     "proxyquire": "^2.1.3",
+    "typescript": "^5.9.3",
     "vitest": "^4.0.8"
   },
   "dependencies": {

package.json

@@ -0,0 +1,7 @@
+// example module where typechecking should be working both in code editors and via `tsc`
+
+import Mixpanel from "../lib/mixpanel-node.js";
+
+const mp = Mixpanel.init("asjdf", { local_flags_config: {} });
+mp.track("test event");
+mp.local_flags?.getVariantValue("color", "blue", { distinct_id: "user_1" });

tscheck/example.ts

@@ -0,0 +1,41 @@
+{
+  // Visit https://aka.ms/tsconfig to read more about this file
+  "compilerOptions": {
+    // File Layout
+    // "rootDir": "./lib",
+    // "outDir": "./dist",
+
+    // Environment Settings
+    // See also https://aka.ms/tsconfig/module
+    "module": "nodenext",
+    "target": "esnext",
+
+    // For nodejs:
+    "lib": ["esnext"],
+    "types": ["node"],
+
+    "noEmit": true,
+
+    "esModuleInterop": true,
+
+    // Stricter Typechecking Options
+    "noUncheckedIndexedAccess": true,
+    "exactOptionalPropertyTypes": true,
+
+    // Style Options
+    // "noImplicitReturns": true,
+    // "noImplicitOverride": true,
+    // "noUnusedLocals": true,
+    // "noUnusedParameters": true,
+    // "noFallthroughCasesInSwitch": true,
+    // "noPropertyAccessFromIndexSignature": true,
+
+    // Recommended Options
+    "strict": true,
+    // "verbatimModuleSyntax": true,
+    "isolatedModules": true,
+    "noUncheckedSideEffectImports": true,
+    "moduleDetection": "force",
+    "skipLibCheck": true,
+  }
+}