diff --git a/.eslintrc.js b/.eslintrc.js
index edaa436791..5e7b9c9da5 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -65,6 +65,7 @@ module.exports = {
         "radix": 2,
         "valid-typeof": 2,
         "no-implicit-globals": [2],
+        "no-unused-expressions": [2, { "allowShortCircuit": true, "allowTernary": true, "allowTaggedTemplates": true}],
 
         // es2015 features
         "require-yield": 2,
diff --git a/src/server/firefox/ffAccessibility.ts b/src/server/firefox/ffAccessibility.ts
index ce057dba0f..bac79b9646 100644
--- a/src/server/firefox/ffAccessibility.ts
+++ b/src/server/firefox/ffAccessibility.ts
@@ -78,7 +78,6 @@ class FFAXNode implements accessibility.AXNode {
     this._expanded = !!payload.expanded;
     this._name = this._payload.name;
     this._role = this._payload.role;
-    this._cachedHasFocusableChild;
   }
 
   _isPlainTextField(): boolean {
diff --git a/src/server/pipeTransport.ts b/src/server/pipeTransport.ts
index 6ea96509ea..40c37fb1b1 100644
--- a/src/server/pipeTransport.ts
+++ b/src/server/pipeTransport.ts
@@ -35,9 +35,9 @@ export class PipeTransport implements ConnectionTransport {
       this._closed = true;
       if (this.onclose)
         this.onclose.call(null);
-    }),
-    pipeRead.on('error', e => debugLogger.log('error', e)),
-    pipeWrite.on('error', e => debugLogger.log('error', e)),
+    });
+    pipeRead.on('error', e => debugLogger.log('error', e));
+    pipeWrite.on('error', e => debugLogger.log('error', e));
     this.onmessage = undefined;
     this.onclose = undefined;
   }
diff --git a/src/trace/harTracer.ts b/src/trace/harTracer.ts
index 54feb75e56..38dccbbdf6 100644
--- a/src/trace/harTracer.ts
+++ b/src/trace/harTracer.ts
@@ -188,7 +188,7 @@ class HarContextTracer {
     const harEntry = this._entries.get(response.request())!;
     // Rewrite provisional headers with actual
     const request = response.request();
-    harEntry.request.headers = request.headers().map(header => ({ name: header.name, value: header.value })),
+    harEntry.request.headers = request.headers().map(header => ({ name: header.name, value: header.value }));
     harEntry.request.cookies = cookiesForHar(request.headerValue('cookie'), ';');
     harEntry.request.postData = postDataForHar(request) || undefined;
 
diff --git a/test/cli/cli-codegen.spec.ts b/test/cli/cli-codegen.spec.ts
index eab0f00c31..a5e44453e8 100644
--- a/test/cli/cli-codegen.spec.ts
+++ b/test/cli/cli-codegen.spec.ts
@@ -111,7 +111,7 @@ describe('cli codegen', (test, { browserName, headful }) => {
     expect(selector).toBe('input[name="name"]');
 
     const messages: any[] = [];
-    page.on('console', message => messages.push(message)),
+    page.on('console', message => messages.push(message));
     await Promise.all([
       recorder.waitForActionPerformed(),
       recorder.waitForOutput('press'),
@@ -161,7 +161,7 @@ describe('cli codegen', (test, { browserName, headful }) => {
     const messages: any[] = [];
     page.on('console', message => {
       messages.push(message);
-    }),
+    });
     await Promise.all([
       recorder.waitForActionPerformed(),
       recorder.waitForOutput('press'),
@@ -182,7 +182,7 @@ describe('cli codegen', (test, { browserName, headful }) => {
     const messages: any[] = [];
     page.on('console', message => {
       messages.push(message);
-    }),
+    });
     await Promise.all([
       recorder.waitForActionPerformed(),
       recorder.waitForOutput('press'),
diff --git a/test/page-route.spec.ts b/test/page-route.spec.ts
index a3349b0ef0..cf62c89e3d 100644
--- a/test/page-route.spec.ts
+++ b/test/page-route.spec.ts
@@ -424,7 +424,7 @@ it('should not throw "Invalid Interception Id" if the request was cancelled', as
   await page.setContent('<iframe></iframe>');
   let route = null;
   await page.route('**/*', async r => route = r);
-  page.$eval('iframe', (frame, url) => frame.src = url, server.EMPTY_PAGE),
+  page.$eval('iframe', (frame, url) => frame.src = url, server.EMPTY_PAGE);
   // Wait for request interception.
   await page.waitForEvent('request');
   // Delete frame to cause request to be canceled.