TikTok Front End Engineer Interview Process

During the first technical screening for the TikTok Frontend Engineer role, candidates can expect a thorough assessment of their technical skills, particularly in frontend development, React.js, HTTP concepts, and JavaScript proficiency.

Led by a senior frontend engineer, the session typically begins with a self-introduction from the candidate, followed by questions about the past projects listed on your resume. So, for instance, the interviewer may inquire about your “most challenging project” or “most successful project” to gauge your experience levels and problem-solving skills.

Once the resume-related questions are addressed, the interviewer will then delve into frontend-specific topics. This may include inquiries about your familiarity with React Hooks, dependency arrays, and so on.

Following this, you may be asked questions on basic networking concepts (particularly related to HTTP) as well as JavaScript-based questions:

• Can you provide a brief overview of your background and experience?
• What motivated you to apply for a position at TikTok?
• What drew you specifically to the field of Front-end Engineering?
• Could you discuss a project from your past experience that presented significant challenges?
• Which React Hooks have you utilised in your development projects?
• Could you elaborate on the intricacies of the useEffect hook?
• What is the purpose of the dependency array in useEffect, and how does it function?
• Why does useEffect only execute once when the component is mounted with an empty dependency array?
• What are the implications of including an object or an array in the dependency array?
• What are the implications of including an object or an array in the dependency array?
• What happens if a ref is passed in the dependency array?
• What is the difference between useLayoutEffect and useEffect? When should you use each?
• Please talk about HTTP caching.
• Between eTag or Last Modified, which one is preferred? Why?
• What is the response body of 304?
• Explain the concept of the Event Loop in JavaScript and how it handles asynchronous operations.
• Differentiate between micro tasks and macro tasks in the context of the Event Loop.
• Implement the .get method of the lodash library in vanilla JavaScript.

During the second technical screening, candidates can again expect to interact with a senior frontend engineer who will delve deeper into your technical skills and experience.

This interview also begins with a self-introduction, and then the interviewer proceeds to ask questions related to your resume—focusing on your experience with writing unit tests and end-to-end (E2E) tests in past projects. The idea is to assess your familiarity with testing methodologies and best practices.

The technical screening 2 typically concludes with a whiteboard question, often from platforms like LeetCode. So, for example, it may be a medium-level string manipulation problem.

• Can you explain the key differences between a Map object and a regular JavaScript object?
• What are some emerging trends or technologies in the JavaScript ecosystem that you find interesting?
• Can you discuss some of the new features and improvements introduced in React 18?
• Write a function to determine if a string is a palindrome.
• Implement a function to reverse a linked list.
• What are React hooks, and how do they differ from class-based component life cycles?

The third technical interview for the TikTok Frontend Engineer role is quite different from the previous rounds. There's no self-introduction; they dive straight into the technical stuff.

First up, they hit you with a LeetCode Medium question, usually a spin on something like 3Sum. It's a test of your coding skills and ability to solve problems efficiently.

Then comes the barrage of frontend questions:

• They might ask about React Fibre and its role in improving rendering performance.
• Expect questions on how HTTP works, covering the basics of request-response cycles, methods, status codes, what the s is in HTTPs, etc.

Once that's done, get ready for a front-end system design question. So, for example, it could be about designing a Typeahead front-end system, where you may have to delve into architecture, data flow, and implementation details for about 20 minutes.

By the end of these three rounds, they will have grilled you on everything from JavaScript to React, networking, algorithms, and system design. So, if you're prepping for the TikTok front-end interview, make sure you prepare extensively.

The onsite interview process covers a lot of ground in frontend development, from coding skills to system design and core fundamentals. Here are insights into the onsite interview process for the TikTok Frontend Engineer role:

• DSA Coding Rounds (1-2 Rounds):

These rounds are all about data structures and algorithms. Some companies prefer coding in JavaScript for these rounds, so it's good to brush up on your JS skills.

• Scalability and Architecture Round:

Here, they're looking for your ability to design scalable systems, especially with a focus on frontend-related questions. It's important to showcase your understanding of how to architect systems that can handle large-scale usage while keeping performance and reliability in check.

• Advanced Frontend System Design Round (for Experienced Candidates >5 Years):

If you've got more than five years of experience, you'll likely face this round. It's all about demonstrating your ability to design frontend systems that perform well, are accessible, and modular.

• Core Front-end Round (for Less Experienced Candidates <5 Years):

This one's for candidates with less than five years of experience. Expect questions covering a range of frontend concepts, from medium to high difficulty.

• JavaScript Fundamentals Round:

In this round, they'll test your knowledge of JavaScript language and libraries, as well as the DOM. You'll need to solve problems using JavaScript without relying on frameworks like React.

• Implement a Queue using Stacks.
• Merge sorted arrays.
• Uncompress a string.
• Implement Promise.all().
• Validate a string of parentheses.
• Create an interval.
• Implement _.get().
• Implement Array.prototype.flat().
• Find the longest substring with unique characters.
• Explain the differences between Cookie, localStorage, and sessionStorage.
• What is HTTP Cache and how does it work?
• Define CSRF and explain methods to prevent it.
• How does HTTPS work?
• Describe the workings of HTTP and explain HTTP/2.

So, after tackling the three technical rounds, you proceed to the HR round. Mind you— it is just as crucial as the tech rounds.

First off, the HR rep gives you a rundown of the company culture and what the team you're interviewing for is currently working on. Next, it's behavioural interview questions—these can range from how you handle teamwork and conflict to your problem-solving approach and communication style. It's crucial to prep for these questions and have examples ready to demonstrate your fit with the company culture.

Remember, the HR questions are all about assessing your alignment with the company's values and how you'd contribute to the team dynamic. So, do your homework on the company culture beforehand—it'll definitely pay off.