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.
In Pug, to extend a layout, you use the extends keyword and to fill a block within the layout, you use the ______ keyword.
- include
- fill
- block
- insert
In Pug, the extends keyword is used to extend a layout, and the block keyword is used to fill a block within the layout. This allows you to create modular and reusable templates. The other options do not serve the same purpose in Pug.
How does JavaScript's dynamic typing affect variable assignments and operations?
- It enforces strict type checking.
- It allows variables to change type during runtime.
- It requires explicit type annotations for all variables.
- It prevents type errors at compile time.
JavaScript's dynamic typing allows variables to change their data type during runtime. Unlike languages with static typing, you don't need to specify the data type of a variable explicitly.
In a RESTful API, which HTTP method corresponds to the Update operation in CRUD?
- GET
- POST
- PUT
- DELETE
In a RESTful API, the PUT HTTP method corresponds to the Update operation in CRUD (Create, Read, Update, Delete). It is used to update or modify an existing resource on the server.
Why is it advantageous to use stubbing when dealing with external services or APIs in tests?
- Stubbing allows you to make actual API calls during testing.
- Stubbing provides better performance in tests.
- Stubbing isolates your tests from the external services, making tests more reliable and faster.
- Stubbing is required by external services for testing.
It is advantageous to use stubbing when dealing with external services or APIs in tests because stubbing isolates your tests from the actual external services, making tests more reliable and faster. With stubbing, you can control the responses from external services, ensuring that your tests are not affected by changes or issues with the real services. Options (1), (2), and (4) do not accurately describe the advantages of stubbing in this context.