Senior Software Engineer Mock Interview

Practice 47 Senior Software Engineer interview questions covering system design, architecture decisions, and technical leadership.

Question 14 of 47

What is the difference between blocking and non-blocking calls in JavaScript?

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William Swansen

William Swansen has worked in the employment assistance realm since 2007. He is an author, job search strategist, and career advisor who helps individuals worldwide and in various professions to find their ideal careers.

During an interview for a senior software engineer's position, you will be asked about many different technologies used in the job. Some of these questions will ask you to compare two different technologies which are similar but have different functions or outcomes. Demonstrating your knowledge of these differences will impress the interviewer and satisfy their curiosity about your understanding of the topic.

William Swansen

"The key difference between blocking and non-blocking calls in JavaScript is that the first one is a synchronous operation and the other is asynchronous. Blocking calls require JavaScript operations to wait until a non-Javascript operation provides input or output or finishes its execution. Non-blocking JavaScript calls can execute operations synchronous with other pieces of the script. It is important to know this since JavaScript is a single-threaded executable and can only execute code in a specific order, waiting for the previous operation to be completed before it starts the next one. Executing non-blocking calls overcomes this limitation and helps programs run faster."

William Swansen

When responding to a question like this, start by defining each term, then briefly compare them, stating their features and benefits. Quickly contrast them, stating how they differ, and finish by possibly providing an example to illustrate your answer. This methodology will allow you to organize your answer for any question asking you to compare two terms or technologies.

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Anonymous Answer

A blocking call is otherwise known as a synchronous operation and a non-blocking call is an asynchronous operation. A synchronous JavaScript operation waits for another process to finish before moving on to the next part of the code. An asynchronous operation does not wait for the operation to finish and instead proceeds on with the rest of the code execution. In the early days of JavaScript, callbacks were used in frameworks like Ajax to replicate synchronous-like behavior and would provide the operation with a callback function to be executed once the process was complete. Later on, Promises were introduced to JavaScript which allowed for an executable call chain to be defined in a synchronous order with a catch statement at the end of the chain. And more recently, the async-await functionality was added to JavaScript that allows you to easily specify any section of code that must be executed synchronously.

Amanda's Feedback

Excellent! You've explained the difference between blocking and non-blocking calls simply and clearly. Consider expanding this answer to specify when or how you typically use each, showing the interviewer that you not only understand the functionality but when each is best used.

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47Senior Software Engineer Interview Questions & Answers

Technical

1.Can you discuss how functional programming differs from object-oriented programming?

Technical

2.Do you recommend using a microservice approach or a monolithic app when developing a software program?

Operational

3.Please describe how you would refactor a class for easier testing.

Operational Software Enginee

4.If you were asked about addressing a website's degrading performance, what recommendations would you make to correct this?

Technical

5.Can you discuss responsive design and the differences between fixed and fluid layouts?

Operational

6.What methodologies do you use to ensure that your program will scale?

Operational

7.When do you use black box testing and white box testing to test a website?

Operational

8.Describe for me some of the techniques you use to monitor the performance of your software.

Operational

9.Describe to me how you organize CSS files and why you prefer your approach.

Operational

10.How do you structure data tables if you create a program to manage a point of sale operation?

Technical

11.How does HTML5 use web workers, and why is this important?

Operational

12.What is harding and how is it used in the programs you create?

Operational

13.What criteria do you use when deciding whether to use a SQL solution instead of NoSQL for your project?

Tehcnical

14.What is the difference between blocking and non-blocking calls in JavaScript?

Operational

15.Please walk me through the process you use to decide between two technologies when both will get the job done.

Operational

16.Can you demonstrate how you would implement Dijkstra's Shortest Path in the programming language you normally work with?

Operational

17.Describe to me how you would implement a linear search in JavaScript.

Operational

18.As a senior software engineer, you will be expected to lead a development team. How would you prioritize the tasks you assign to each developer to improve collaboration?

Technical

19.How does a data array differ from a stack?

Operational

20.Please walk me through the process you use when assigned a programming project, starting with defining the requirements and going through delivery.

Technical

21.What is a stack in the context of software development, and how can it be used to simplify the SDLC?

Operational

22.What programming languages do you recommend an organization like ours use to create software to support our operations?

Operational

23.How do you direct your team to identify and correct errors in their code?

Discovery

24.What experience do you have with Agile software development? What do you like about this methodology?

Operational

25.Walk me through the process of creating an SQL database for time-series information?

Discovery

26.Tell me about a recent project you managed that relied on a source control system to direct your team.

Discovery

27.Are you familiar with service-oriented architectures? When do you use them?

Discovery

28.What was the biggest development team you have managed and what was the biggest challenge you faced?

Operational

29.When do you feel it is appropriate to follow "procedural" logic when developing software?

Operational

30.Can you describe the design patterns you use and when you use them?

Behavioral

31.Can you describe a time you were asked to do something you had never done before? How did you react?

Behavioral

32.Please describe a situation where you needed to adapt a process, procedure, or technology differently from how you usually did things.

Behavioral

33.Can you recall a time you were assigned a task that wasn't a part of your job description? How did you handle this, and what was the outcome?

Behavioral

34.Tell me about an aspect of your profession that makes you the most satisfied, energized, and productive at work.

Behavioral

35.What's a misconception your coworkers have about you, and why do you believe they feel this way?

Behavioral

36.Can you give me an example of when you had to work with someone difficult to get along with? How did you handle the situation?

Behavioral

37.Please tell me about a time when something major didn't go according to plan at work.

Behavioral

38.Describe a situation where you needed to persuade someone about an idea or process.

Behavioral

39.Can you give me an example of a time you led by example and describe what you did and how your team reacted?

Behavioral

40.Tell me about a difficult decision you had to make in one of your previous roles.

Behavioral

41.Can you recall a time your manager was unavailable when a situation arose that demanded an immediate resolution? How did you react?

Discovery

42.When was the last occasion you asked for direct feedback from your manager?

Discovery

43.Can you tell me what your home network consists of?

Discovery

44.What is a professional achievement that you are proud of?

Discovery

45.Why did you choose to interview with our organization rather than with others in our industry?

Discovery

46.What's the most interesting thing about you that I didn't see on your resume?

Discovery

Senior Software Engineer Mock Interview

What is the difference between blocking and non-blocking calls in JavaScript?

47Senior Software Engineer Interview Questions & Answers

1.Can you discuss how functional programming differs from object-oriented programming?

2.Do you recommend using a microservice approach or a monolithic app when developing a software program?

3.Please describe how you would refactor a class for easier testing.

4.If you were asked about addressing a website's degrading performance, what recommendations would you make to correct this?

5.Can you discuss responsive design and the differences between fixed and fluid layouts?

6.What methodologies do you use to ensure that your program will scale?

7.When do you use black box testing and white box testing to test a website?

8.Describe for me some of the techniques you use to monitor the performance of your software.

9.Describe to me how you organize CSS files and why you prefer your approach.

10.How do you structure data tables if you create a program to manage a point of sale operation?

11.How does HTML5 use web workers, and why is this important?

12.What is harding and how is it used in the programs you create?

13.What criteria do you use when deciding whether to use a SQL solution instead of NoSQL for your project?

14.What is the difference between blocking and non-blocking calls in JavaScript?

15.Please walk me through the process you use to decide between two technologies when both will get the job done.

16.Can you demonstrate how you would implement Dijkstra's Shortest Path in the programming language you normally work with?

17.Describe to me how you would implement a linear search in JavaScript.

18.As a senior software engineer, you will be expected to lead a development team. How would you prioritize the tasks you assign to each developer to improve collaboration?

19.How does a data array differ from a stack?

20.Please walk me through the process you use when assigned a programming project, starting with defining the requirements and going through delivery.

21.What is a stack in the context of software development, and how can it be used to simplify the SDLC?

22.What programming languages do you recommend an organization like ours use to create software to support our operations?

23.How do you direct your team to identify and correct errors in their code?

24.What experience do you have with Agile software development? What do you like about this methodology?

25.Walk me through the process of creating an SQL database for time-series information?

26.Tell me about a recent project you managed that relied on a source control system to direct your team.

27.Are you familiar with service-oriented architectures? When do you use them?

28.What was the biggest development team you have managed and what was the biggest challenge you faced?

29.When do you feel it is appropriate to follow "procedural" logic when developing software?

30.Can you describe the design patterns you use and when you use them?

31.Can you describe a time you were asked to do something you had never done before? How did you react?

32.Please describe a situation where you needed to adapt a process, procedure, or technology differently from how you usually did things.

33.Can you recall a time you were assigned a task that wasn't a part of your job description? How did you handle this, and what was the outcome?

34.Tell me about an aspect of your profession that makes you the most satisfied, energized, and productive at work.

35.What's a misconception your coworkers have about you, and why do you believe they feel this way?

36.Can you give me an example of when you had to work with someone difficult to get along with? How did you handle the situation?

37.Please tell me about a time when something major didn't go according to plan at work.

38.Describe a situation where you needed to persuade someone about an idea or process.

39.Can you give me an example of a time you led by example and describe what you did and how your team reacted?

40.Tell me about a difficult decision you had to make in one of your previous roles.

41.Can you recall a time your manager was unavailable when a situation arose that demanded an immediate resolution? How did you react?

42.When was the last occasion you asked for direct feedback from your manager?

43.Can you tell me what your home network consists of?

44.What is a professional achievement that you are proud of?

45.Why did you choose to interview with our organization rather than with others in our industry?

46.What's the most interesting thing about you that I didn't see on your resume?

47.What motivated you to make a move from your current role?