Utilizing closures with caution is essential as they can lead to potential memory leaks due to retained ________.
- Variables
- Functions
- References
- Objects
Closures retain references to their containing scope, which includes variables and functions. If not managed carefully, this can lead to memory leaks as these references may prevent objects from being garbage collected.
How can the process object be used to handle application termination in Node.js?
- process.exit()
- process.end()
- process.terminate()
- process.halt()
In Node.js, you can use process.exit() to gracefully terminate a Node.js application. It allows you to specify an exit code. The other options, such as process.end(), process.terminate(), and process.halt(), are not valid methods for application termination.
Which of the following is a primary use case for stubbing in tests?
- Capturing and verifying function calls
- Simulating the behavior of a function or method
- Mocking external dependencies
- Generating random test data
Stubbing in tests is often used to simulate the behavior of a function or method, allowing you to control its responses for testing purposes. It's especially useful when you want to isolate the code under test and ensure that certain functions return specific values or execute specific code paths.
How can you ensure the security of file uploads in a web application?
- Use an unauthenticated endpoint
- Limit file size
- Disallow specific file types
- Perform server-side validation
To ensure the security of file uploads in a web application, it's crucial to perform server-side validation. This includes checking the file's content type, verifying its size, and possibly scanning it for malware. Other important security measures include limiting file sizes to prevent denial-of-service attacks and disallowing specific file types to prevent the upload of potentially harmful files. Using an unauthenticated endpoint is not recommended as it could lead to security vulnerabilities.
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.
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.