In JavaScript, altering an object’s prototype at runtime can lead to ______ performance impacts.
- Positive
- Negative
- No
- Minimal
In JavaScript, altering an object's prototype at runtime can lead to "Negative" performance impacts. Modifying prototypes at runtime can cause performance bottlenecks, as it can affect the behavior of all objects that share the same prototype. It's generally recommended to avoid such runtime modifications for performance reasons.
What is the difference between the == and === operators in JavaScript?
- == compares values for equality, === compares values and types for equality
- == compares values and types for equality, === compares values for equality
- == is used for assignment, === is used for comparison
- == performs a deep comparison, === performs a shallow comparison
In JavaScript, == (loose equality) compares values for equality but performs type coercion if the operands have different types. === (strict equality) compares both values and types for equality without type coercion. Option 1 correctly describes this important distinction.
How does ESLint's --fix option handle issues that it can't automatically fix?
- ESLint raises an error and stops
- It logs the issues without attempting to fix them
- It automatically disables the rule causing the issue
- It leaves the issues as is
When ESLint's --fix option encounters issues it can't automatically fix, it will disable the rule causing the issue to prevent further errors. This allows ESLint to continue running and fix as many issues as possible without breaking. The other options do not accurately describe how --fix behaves.
How can you ensure that your project’s dependencies are secure and up-to-date?
- Ignore dependency updates to maintain stability.
- Regularly review and update dependencies using a tool like npm audit or yarn audit.
- Rely on the package maintainers to keep dependencies secure.
- Never update dependencies to avoid breaking changes.
To ensure that your project's dependencies are secure and up-to-date, you should regularly review and update them using tools like npm audit or yarn audit. These tools help identify and address security vulnerabilities. Ignoring updates may lead to security risks, and relying solely on package maintainers is not a recommended practice. Avoiding updates altogether is not a solution as it can lead to outdated and potentially insecure dependencies.
In Jest, to isolate a module from its dependencies for more focused unit testing, you would use ______.
- mock
- stub
- spy
- inject
In Jest, you can use the mock function to isolate a module from its dependencies. This allows you to replace the real dependencies with mock implementations for focused unit testing.
You are developing a critical system where the cost of failure is very high. How would you design your testing strategy to ensure the reliability and stability of the system?
- Conduct extensive Unit Testing
- Rely on Beta Testing by end-users
- Implement Continuous Integration and Continuous Deployment (CI/CD) pipelines
- Perform thorough Regression Testing and use Automated Testing
To ensure the reliability and stability of a critical system, thorough Regression Testing and the use of Automated Testing are essential. These techniques help catch potential issues early and maintain system stability. Extensive Unit Testing alone may not cover all scenarios, and Beta Testing may be too risky for critical systems. CI/CD pipelines support automation but should be combined with robust testing.
You are optimizing the performance of a web application that uses EJS for rendering views. The views have a lot of dynamic content and are currently slow to render. How would you approach optimizing the rendering performance of the EJS templates?
- Implement caching mechanisms for frequently accessed templates using a caching library like Redis.
- Minimize the use of JavaScript in templates and offload complex logic to the server-side to reduce client-side rendering time.
- Precompile EJS templates into JavaScript functions to reduce runtime rendering overhead.
- Increase the client-side rendering capabilities by using a JavaScript framework like React or Angular.
To optimize the rendering performance of EJS templates, one effective approach is to precompile EJS templates into JavaScript functions. This reduces the runtime rendering overhead and improves the efficiency of rendering dynamic content.
In JavaScript, a closure is created when an inner function accesses the ________ of an outer function after the outer function has executed.
- parameters
- variables
- methods
- properties
In JavaScript, a closure is created when an inner function accesses the variables of an outer function after the outer function has executed. Closures allow inner functions to "remember" and access the variables of their containing (outer) function even after the outer function has finished executing. This is a fundamental concept for managing scope and data privacy in JavaScript.
You are tasked with developing a real-time chat application where low latency and high availability are critical. Which type of database would be the most suitable, and what considerations should you have in mind regarding data consistency and partitioning?
- Relational Database
- NoSQL Database
- Graph Database
- In-Memory Database
For a real-time chat application, a NoSQL database would be most suitable due to its ability to handle high concurrency and unstructured data. Considerations for data consistency would involve choosing an appropriate consistency model, like eventual consistency, and partitioning data for scalability and low latency.
How does cache eviction strategy LRU (Least Recently Used) work?
- LRU removes the item that was accessed most recently.
- LRU removes the item that was accessed least recently.
- LRU removes the item with the smallest key.
- LRU removes items randomly.
LRU (Least Recently Used) eviction strategy removes the item from the cache that was accessed the least recently. This ensures that the cache retains the most recently accessed items, optimizing for cache hits.