diff --git a/src/DeviceDescriptors.js b/src/DeviceDescriptors.ts
similarity index 98%
rename from src/DeviceDescriptors.js
rename to src/DeviceDescriptors.ts
index 5d586d779a4..945e5cadf7f 100644
--- a/src/DeviceDescriptors.js
+++ b/src/DeviceDescriptors.ts
@@ -14,7 +14,20 @@
  * limitations under the License.
  */
 
-module.exports = [
+interface Device {
+  name: string;
+  userAgent: string;
+  viewport: {
+    width: number;
+    height: number;
+    deviceScaleFactor: number;
+    isMobile: boolean;
+    hasTouch: boolean;
+    isLandscape: boolean;
+  };
+};
+
+const devices: Device[] = [
   {
     'name': 'Blackberry PlayBook',
     'userAgent': 'Mozilla/5.0 (PlayBook; U; RIM Tablet OS 2.1.0; en-US) AppleWebKit/536.2+ (KHTML like Gecko) Version/7.2.1.0 Safari/536.2+',
@@ -868,5 +881,15 @@ module.exports = [
     }
   }
 ];
-for (const device of module.exports)
-  module.exports[device.name] = device;
+
+type DevicesMap = {
+  [name: string]: Device;
+};
+
+const devicesMap: DevicesMap = {};
+
+for (const device of devices) {
+  devicesMap[device.name] = device;
+}
+
+export = devicesMap;
diff --git a/tsconfig.json b/tsconfig.json
index 815fab9b1be..baf9d96a5a4 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -4,7 +4,8 @@
     "checkJs": true,
     "outDir": "./lib",
     "target": "ESNext",
-    "moduleResolution": "node"
+    "moduleResolution": "node",
+    "module": "CommonJS"
   },
   "include": [
     "src"
diff --git a/utils/doclint/cli.js b/utils/doclint/cli.js
index ed58a4b43a5..96eb000a723 100755
--- a/utils/doclint/cli.js
+++ b/utils/doclint/cli.js
@@ -36,31 +36,29 @@ async function run() {
   let changedFiles = false;
 
   // Documentation checks.
-  {
-    const readme = await Source.readFile(path.join(PROJECT_DIR, 'README.md'));
-    const contributing = await Source.readFile(path.join(PROJECT_DIR, 'CONTRIBUTING.md'));
-    const api = await Source.readFile(path.join(PROJECT_DIR, 'docs', 'api.md'));
-    const troubleshooting = await Source.readFile(path.join(PROJECT_DIR, 'docs', 'troubleshooting.md'));
-    const mdSources = [readme, api, troubleshooting, contributing];
+  const readme = await Source.readFile(path.join(PROJECT_DIR, 'README.md'));
+  const contributing = await Source.readFile(path.join(PROJECT_DIR, 'CONTRIBUTING.md'));
+  const api = await Source.readFile(path.join(PROJECT_DIR, 'docs', 'api.md'));
+  const troubleshooting = await Source.readFile(path.join(PROJECT_DIR, 'docs', 'troubleshooting.md'));
+  const mdSources = [readme, api, troubleshooting, contributing];
 
-    const preprocessor = require('./preprocessor');
-    messages.push(...await preprocessor.runCommands(mdSources, VERSION));
-    messages.push(...await preprocessor.ensureReleasedAPILinks([readme], VERSION));
+  const preprocessor = require('./preprocessor');
+  messages.push(...await preprocessor.runCommands(mdSources, VERSION));
+  messages.push(...await preprocessor.ensureReleasedAPILinks([readme], VERSION));
 
-    const browser = await puppeteer.launch();
-    const page = await browser.newPage();
-    const checkPublicAPI = require('./check_public_api');
-    const jsSources = await Source.readdir(path.join(PROJECT_DIR, 'lib'));
-    messages.push(...await checkPublicAPI(page, mdSources, jsSources));
+  const browser = await puppeteer.launch();
+  const page = await browser.newPage();
+  const checkPublicAPI = require('./check_public_api');
+  const jsSources = await Source.readdir(path.join(PROJECT_DIR, 'lib'));
+  messages.push(...await checkPublicAPI(page, mdSources, jsSources));
 
-    await browser.close();
+  await browser.close();
 
-    for (const source of mdSources) {
-      if (!source.hasUpdatedText())
-        continue;
-      await source.save();
-      changedFiles = true;
-    }
+  for (const source of mdSources) {
+    if (!source.hasUpdatedText())
+      continue;
+    await source.save();
+    changedFiles = true;
   }
 
   // Report results.