diff --git a/.eslintrc.js b/.eslintrc.js
index a0bf98660eb0e..85305e5027cc1 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -102,12 +102,17 @@ module.exports = {
     },
     "overrides": [
         {
-            // apply TypeScript linting to the TS files in src/
-            "files": ["src/*.ts"],
+            "files": ["*.ts"],
             "extends": [
                 'plugin:@typescript-eslint/eslint-recommended',
                 'plugin:@typescript-eslint/recommended',
-            ]
+            ],
+            "rules": {
+                "no-unused-vars": 0,
+                "@typescript-eslint/no-unused-vars": 2,
+                "semi": 0,
+                "@typescript-eslint/semi": 2
+            }
         }
     ]
 };
diff --git a/src/Dialog.js b/src/Dialog.ts
similarity index 66%
rename from src/Dialog.js
rename to src/Dialog.ts
index cbdc271916937..8e0e0c0be45db 100644
--- a/src/Dialog.js
+++ b/src/Dialog.ts
@@ -14,48 +14,46 @@
  * limitations under the License.
  */
 
-const {assert} = require('./helper');
+import helpers = require('./helper');
+
+const {assert} = helpers;
+
+enum DialogType {
+  Alert = 'alert',
+  BeforeUnload = 'beforeunload',
+  Confirm = 'confirm',
+  Prompt = 'prompt'
+}
 
 class Dialog {
-  /**
-   * @param {!Puppeteer.CDPSession} client
-   * @param {string} type
-   * @param {string} message
-   * @param {(string|undefined)} defaultValue
-   */
-  constructor(client, type, message, defaultValue = '') {
+  static Type = DialogType;
+
+  private _client: Puppeteer.CDPSession;
+  private _type: DialogType;
+  private _message: string;
+  private _defaultValue: string;
+  private _handled = false;
+
+  constructor(client: Puppeteer.CDPSession, type: DialogType, message: string, defaultValue = '') {
     this._client = client;
     this._type = type;
     this._message = message;
-    this._handled = false;
     this._defaultValue = defaultValue;
   }
 
-  /**
-   * @return {string}
-   */
-  type() {
+  type(): DialogType {
     return this._type;
   }
 
-  /**
-   * @return {string}
-   */
-  message() {
+  message(): string {
     return this._message;
   }
 
-  /**
-   * @return {string}
-   */
-  defaultValue() {
+  defaultValue(): string {
     return this._defaultValue;
   }
 
-  /**
-   * @param {string=} promptText
-   */
-  async accept(promptText) {
+  async accept(promptText?: string): Promise<void> {
     assert(!this._handled, 'Cannot accept dialog which is already handled!');
     this._handled = true;
     await this._client.send('Page.handleJavaScriptDialog', {
@@ -64,7 +62,7 @@ class Dialog {
     });
   }
 
-  async dismiss() {
+  async dismiss(): Promise<void> {
     assert(!this._handled, 'Cannot dismiss dialog which is already handled!');
     this._handled = true;
     await this._client.send('Page.handleJavaScriptDialog', {
@@ -73,11 +71,4 @@ class Dialog {
   }
 }
 
-Dialog.Type = {
-  Alert: 'alert',
-  BeforeUnload: 'beforeunload',
-  Confirm: 'confirm',
-  Prompt: 'prompt'
-};
-
-module.exports = {Dialog};
+export = {Dialog};
diff --git a/utils/doclint/check_public_api/JSBuilder.js b/utils/doclint/check_public_api/JSBuilder.js
index 065dc818c8803..c442b0529b2f9 100644
--- a/utils/doclint/check_public_api/JSBuilder.js
+++ b/utils/doclint/check_public_api/JSBuilder.js
@@ -3,6 +3,7 @@ const path = require('path');
 const Documentation = require('./Documentation');
 module.exports = checkSources;
 
+
 /**
  * @param {!Array<!import('../Source')>} sources
  */
@@ -30,7 +31,23 @@ function checkSources(sources) {
   const classes = [];
   /** @type {!Map<string, string>} */
   const inheritance = new Map();
-  sourceFiles.filter(x => !x.fileName.includes('node_modules')).map(x => visit(x));
+
+  const sourceFilesNoNodeModules = sourceFiles.filter(x => !x.fileName.includes('node_modules'));
+  const sourceFileNamesSet = new Set(sourceFilesNoNodeModules.map(x => x.fileName));
+  sourceFilesNoNodeModules.map(x => {
+    if (x.fileName.includes('/lib/')) {
+      const potentialTSSource = x.fileName.replace('lib', 'src').replace('.js', '.ts');
+      if (sourceFileNamesSet.has(potentialTSSource)) {
+        /* Not going to visit this file because we have the TypeScript src code
+         * which we'll use instead.
+         */
+        return;
+      }
+    }
+
+    visit(x);
+  });
+
   const errors = [];
   const documentation = new Documentation(recreateClassesWithInheritance(classes, inheritance));
 
diff --git a/utils/doclint/cli.js b/utils/doclint/cli.js
index 76156bb6cfbf0..0708c8474c8c3 100755
--- a/utils/doclint/cli.js
+++ b/utils/doclint/cli.js
@@ -49,8 +49,13 @@ async function run() {
   const browser = await puppeteer.launch();
   const page = await browser.newPage();
   const checkPublicAPI = require('./check_public_api');
+  const tsSources = await Source.readdir(path.join(PROJECT_DIR, 'src'), 'ts');
+
+  const tsSourcesNoDefinitions = tsSources.filter(source => !source.filePath().endsWith('.d.ts'));
+
   const jsSources = await Source.readdir(path.join(PROJECT_DIR, 'lib'));
-  messages.push(...await checkPublicAPI(page, mdSources, jsSources));
+  const allSrcCode = [...jsSources, ...tsSourcesNoDefinitions];
+  messages.push(...await checkPublicAPI(page, mdSources, allSrcCode));
 
   await browser.close();