In JavaScript, the ______ property is used to set up inheritance between custom types.
- inherit
- prototype
- extend
- object
In JavaScript, the prototype property is used to set up inheritance between custom types. It allows one object to inherit properties and methods from another object. This is a fundamental concept in JavaScript's object-oriented programming model.
How can you ensure that a specific script in package.json runs only after another specified script has successfully completed?
- Using npm's pre and post scripts
- Using conditional statements in JavaScript
- It's not possible to achieve this in package.json
- By using a third-party package
In package.json, you can use pre and post scripts to define the order in which scripts should run. For example, if you want a script to run after another, you can use "pre": "npm run firstScript" and "post": "npm run secondScript". This ensures that secondScript runs after firstScript.
In Express.js, what does the next() function do in middleware?
- Ends the request-response cycle
- Sends an HTTP response
- Passes control to the next middleware function
- Logs a message to the console
In Express.js, the next() function is used in middleware to pass control to the next middleware function in the stack. It allows the request to continue processing through subsequent middleware functions. If you don't call next(), the request-response cycle may be terminated, and subsequent middleware or route handlers won't be executed.
Which of the following is a common technique used for implementing full-text search in databases?
- Regular Expressions
- Binary Search
- Inverted Index
- Depth-First Search
A common technique for implementing full-text search in databases is the use of an inverted index. This index stores a list of words or terms along with the locations where they appear in the documents, making it efficient for searching large volumes of text. Regular expressions, binary search, and depth-first search are not typically used for full-text search in databases.
How does the use of subqueries impact the performance of SQL queries, and how can it be optimized?
- Subqueries can slow down SQL queries significantly. They execute for each row in the outer query result and may lead to performance bottlenecks. Optimization techniques include using JOINs, EXISTS, or rewriting queries as JOINs, ensuring indexes on relevant columns, and limiting the result set size.
- Subqueries have no impact on SQL query performance.
- Subqueries always improve SQL query performance.
- Subqueries should be avoided, but if used, no optimization is possible.
Subqueries can impact SQL query performance negatively if not used carefully. They can lead to increased query execution times, and optimizing them involves using appropriate techniques to minimize their impact.
You have been assigned to optimize the CRUD operations of a microservices-based application where each microservice handles its own database. How would you ensure the consistency and integrity of data across different microservices while performing Create and Update operations?
- Implement a distributed transaction coordinator
- Use REST APIs for communication
- Share a centralized database
- Implement message queues
To ensure the consistency and integrity of data across different microservices in a microservices-based application, implementing a distributed transaction coordinator (Option 1) is a suitable approach. This coordinator can manage transactions across multiple microservices, ensuring that Create and Update operations either succeed or fail together, preserving data integrity. Using REST APIs (Option 2) for communication is a common practice but doesn't guarantee transactional consistency. Sharing a centralized database (Option 3) can create tight coupling and hinder the benefits of microservices. Implementing message queues (Option 4) helps with asynchronous communication but doesn't inherently guarantee data consistency across microservices.
When designing a schema for a SQL database in Node.js, the ______ key is used to establish a relationship between two tables.
- Foreign
- Index
- Primary
- Composite
When designing a schema for a SQL database in Node.js, the Foreign Key is used to establish a relationship between two tables. It creates a link between a field in one table and the primary key of another table, enabling data integrity and referential integrity.
When using Promise.allSettled, the returned array consists of objects, each having a status property that can either be 'fulfilled' or ________.
- 'completed'
- 'resolved'
- 'rejected'
- 'done'
When using Promise.allSettled, the status property of each object in the returned array can either be 'fulfilled' or 'rejected,' depending on the outcome of the individual Promises in the input array.
In a Node.js module, properties added to the global object can be accessed from ________.
- anywhere in the module
- only within the module
- any other module
Properties added to the global object in a Node.js module can be accessed from anywhere in the module, making them globally accessible within that module.
What is the significance of test coverage in a codebase, and how does it impact the development process?
- Test coverage measures the number of lines of code tested; High test coverage guarantees a bug-free codebase; Test coverage is irrelevant for development.
- Test coverage measures the percentage of code executed by tests; It helps identify untested code paths and potential bugs; High test coverage is a valuable metric but doesn't guarantee bug-free code.
- Test coverage measures the number of test cases written; High test coverage means exhaustive testing and zero defects; Test coverage should be minimized to save development time.
- Test coverage is the number of test tools used; High test coverage indicates a comprehensive testing suite; Test coverage depends on project size.
Test coverage measures the percentage of code executed by tests. It helps identify untested code paths, improving code quality. However, it does not guarantee a bug-free codebase, as it depends on the quality of the tests. The other options provide inaccurate definitions or misconceptions about test coverage.