7 Javascript interview questions and answer strategies

Whether you are an interviewer or a job seeker, the ideas inside can benefit you a lot.

What are the main differences between a single application and a microservice architecture? Which is a better choice from the perspective of flexibility and scalability?

Analysis:

This question is used to evaluate the underlying coding knowledge. There are many different answers, so you should pay attention to listening to specific questions and try to answer them comprehensively to demonstrate your understanding of the single application and microservice architecture.

What the interviewer wants to know:

  • Job seeker familiarity with coding
  • Job seekers’ understanding of the pros and cons of different construction methods
  • Whether it has the ability to transition from a single application service to a micro service

Reference answer:

Designing a single-frame architecture is less costly in the short term, but the code is a single cohesive unit in memory. The microservices architecture provides flexibility and extensibility because each component is a separate program.

What is the difference between synchronous and asynchronous programming, and what does asynchronous programming have to do with your JavaScript work?

Analysis:

Asynchronous programming allows for multiple concurrent operations, and it works well for JavaScript programs. This question is used to estimate the coding knowledge of job seekers and a specific understanding of JavaScript.

What the interviewer wants to know:

  • Ability to clearly express the difference between synchronous and asynchronous programming
  • The impact of asynchronous programming on the user interface
  • Understand blocking and impact on performance

Reference answer:

In simple terms, synchronous programming means that code is executed in a linear fashion. These programs usually cannot handle multiple operations at the same time. With asynchronous programming, there is an event loop. A program thread can handle multiple operations. Because JavaScript is often used in the user interface, the ability to run multiple operations at the same time can lead to a better user experience.

Have you used class inheritance and prototype inheritance in JavaScript? why?

Analysis:

This question helps to understand whether a job seeker has JavaScript experience and expertise. Prototypal inheritance is easier and more flexible than class inheritance, which is the preferred method for judging an experienced JavaScript programmer.

What the interviewer wants to know:

  • Whether it prefers prototype inheritance and combination
  • Ability to clarify the reasons for this preference
  • Function inheritance, prototype chain inheritance, prototype delegate and object combination

Reference answer:

When using class inheritance, the instance inherits from the class, which creates a hierarchy. With prototypal inheritance, instances inherit from other objects and can be created from multiple objects. I prefer prototypal inheritance because it is simpler and more flexible.

In your opinion, is class inheritance the right choice? If so, under what circumstances? If not, why?

Analysis:

The job seeker’s answer gives the interviewer a deeper understanding of their experience with JavaScript. Class inheritance makes little sense, and job seekers may say that they don’t. Negative answers are better than lengthy descriptions of appropriate situations, as these are usually based on error messages.

What the interviewer wants to know:

  • Class inheritance is never or almost never the right choice
  • Can the job seeker clarify the reason for his reply?
  • Job seekers have the ability to defend their conclusions with logic

Reference answer:

Class inheritance is almost never the right solution. It can only be used in rare cases.

How do you define functional programming? What is the role of functional programming in JavaScript?

Analysis:

Functional programming is the basic principle of JavaScript currently used. Whether the job seeker can answer this question in full can prove whether their basic knowledge is solid.

What the interviewer wants to know:

  • Mention pure functions and avoid side effects
  • An example of a functional programming language
  • Able to recognize the functional programming of JavaScript and have the ability to use them

Reference answer:

Functional programming allows software to be designed by using pure functions. This method avoids many programming problems such as shared state, side effects, and variable data. It is an alternative to object-oriented programming where the state of the application is usually paired and shared with the methods in the object.

What are the benefits of using functional programming rather than object-oriented programming? Can you provide an example?

Analysis:

Any job seeker with JavaScript experience will use one of these styles, so you should be able to give some thoughts on the pros and cons of each style. This question can help the interviewer measure the depth of the job seeker’s use of JavaScript.

What the interviewer wants to know:

  • Can clarify the advantages and disadvantages of any method
  • Mention issues caused by shared resources
  • Learn how functional programming simplifies applications

Reference answer:

Although I mainly use object-oriented programming, I prefer to use functional programming. This is especially true when using object-oriented programming to encounter different components competing for the same resources.

How do you define one-way data flow and two-way data binding? What is the difference between the two?

Analysis:

This question illustrates the job seeker’s deep understanding of the fundamental principles of JavaScript. Job seekers who are not familiar with these terms may not have the experience required for the position.

What the interviewer wants to know:

  • Ability to define these two concepts clearly and concisely
  • Can clarify the difference between the two concepts
  • Mention the relevant framework

Reference answer:

One-way data flow occurs when the model is a single source of truth, and React is an example. Two-way data binding is the state in which the user interface is dynamically linked to the model data. If the fields in the user interface change, the model will also change, such as Angular.

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