In Node.js, to interact with SQL databases, an ORM like ______ can be used.
- Sequelize
- MongoDB
- Express
- Mongoose
In Node.js, Sequelize is a popular Object-Relational Mapping (ORM) library used to interact with SQL databases. It provides an abstraction layer for working with databases, making it easier to manage and query relational data. Options 2, 3, and 4 are not ORMs and are not used for SQL databases.
In E2E testing, tests are executed in an environment that simulates a ________ user environment.
- production
- controlled
- real
- isolated
In End-to-End (E2E) testing, tests are executed in an environment that simulates a real user environment. This means the tests mimic the actions and interactions of real users with the application, helping ensure that the application works as expected in a production-like setting. While controlled and isolated environments may be used in testing, they are not the primary focus of E2E testing. Production environments are typically not used for testing to avoid risks to the live system.
How can you prevent replay attacks when using OAuth 2.0?
- Use Nonce Values
- Use Long-lived Tokens
- Use Weak Passwords
- Use Static Client IDs
Preventing replay attacks in OAuth 2.0 involves using Nonce values (number used once) to ensure that each request is unique and can't be replayed. Nonces are typically used with authorization codes to add an extra layer of security. The other options are not effective in preventing replay attacks.
Which method is commonly used in Node.js to handle errors in callbacks?
- try...catch
- process.exit()
- console.error()
- callback(error)
In Node.js, it's common to handle errors in callbacks by passing an error object as the first argument to the callback function. This allows the callback to check if an error occurred during the asynchronous operation and take appropriate action. The other options (try...catch, process.exit(), and console.error()) are not used to handle errors in callbacks but serve different purposes.
Which method can be used to add new elements to an array in JavaScript?
- append()
- push()
- add()
- insert()
To add new elements to an array in JavaScript, you should use the push() method. It adds one or more elements to the end of an array. The other options are not valid methods for adding elements to an array in JavaScript.
What is the significance of the process.nextTick() method in Node.js?
- It schedules a callback function to be executed in the next iteration of the event loop, immediately after the current operation is complete.
- It delays the execution of a callback function for a specific number of milliseconds.
- It cancels the execution of a callback function.
- It executes the callback function asynchronously in a new Node.js process.
process.nextTick() is used to schedule a callback function to be executed in the next iteration of the event loop, immediately after the current operation is complete. This allows for efficient asynchronous code execution. The other options do not accurately describe the purpose of process.nextTick().
How can composite indexing be optimized to enhance query performance in relational databases?
- Use covering indexes
- Increase the number of indexed columns
- Avoid indexing on frequently updated columns
- Use B-tree indexes only
Composite indexing can be optimized by using covering indexes, which include all the columns required by a query. This reduces the need for additional table lookups and can significantly enhance query performance. Increasing the number of indexed columns may not always be beneficial as it can increase index maintenance overhead. Indexing frequently updated columns should be avoided to prevent write performance degradation. B-tree indexes are just one type of composite index, and the choice of index type depends on the specific use case.
What is the significance of the tilde (~) symbol in a version number, like ~1.2.3, in semantic versioning?
- It allows upgrades to the specified version and any future versions, including breaking changes.
- It signifies that downgrades are allowed.
- It restricts upgrades to only the specified version.
- It allows upgrades to the specified version and any future backward-compatible versions.
The tilde (~) symbol allows upgrades to the specified version and any future backward-compatible versions while keeping you within the same major version. It's more restrictive than the caret (^).
What does a 0 as the major version (e.g. 0.1.2) signify in semantic versioning?
- It indicates an unstable or experimental version with no guarantees of backward compatibility.
- It signifies the absence of a major version.
- It means that the software is in its initial release and is highly stable.
- It represents a pre-release version.
A 0 as the major version signifies an unstable or experimental version with no guarantees of backward compatibility. It's often used for initial development phases.
When utilizing closures, it is crucial to manage memory effectively to avoid ________.
- memory leaks
- buffer overflows
- infinite loops
- syntax errors
When utilizing closures, it is crucial to manage memory effectively to avoid memory leaks. If closures capture references to objects that are no longer needed, those objects will not be garbage collected, leading to memory leaks. Properly managing references and being mindful of what is captured in closures is essential to prevent this issue.