In JavaScript, the import statement cannot be used in ________.
- functions
- classes
- conditionals
- loops
In JavaScript, the import statement cannot be used inside conditionals (e.g., if statements or loops). It must be used at the top level of a module. This is because module imports are processed before the code is executed, and conditionals are not allowed to change the module structure dynamically.
What is the primary purpose of running the npm init command in a Node.js project?
- To install Node.js
- To create a new Node.js project
- To update Node.js packages
- To uninstall Node.js
The primary purpose of running npm init in a Node.js project is to create a new Node.js project. This command initializes a package.json file, which is essential for managing project dependencies and configurations. It does not install or uninstall Node.js itself.
In which scenario would denormalization be considered a suitable option for query optimization?
- When you want to minimize data redundancy and improve data integrity.
- When you want to improve query performance, even at the cost of some data redundancy and update anomalies.
- Denormalization is never considered a suitable option for query optimization.
- When you want to reduce the size of the database.
Denormalization is considered when you want to optimize read-heavy queries and reduce the number of JOIN operations. It involves introducing redundancy to improve query performance, but it can lead to data anomalies.
In JavaScript, a variable declared without the var, let, or const keyword inside a function becomes a property of the ________ object.
- "window"
- "global"
- "local"
- "this"
In JavaScript, a variable declared without the var, let, or const keyword inside a function becomes a property of the "global" object. This can lead to unexpected behavior, so it's important to declare variables properly.
What strategies can be employed to optimize aggregation queries in NoSQL databases like MongoDB?
- Aggregation queries in NoSQL databases like MongoDB can be optimized by using the aggregation framework provided by MongoDB, creating proper indexes on fields used in aggregation stages, leveraging server resources efficiently, and using projection to limit the output data size.
- Aggregation queries in NoSQL databases cannot be optimized.
- Aggregation queries in NoSQL databases can only be optimized by using raw database queries with no additional strategies.
- Aggregation queries in NoSQL databases should be avoided altogether.
Aggregation queries in NoSQL databases can be resource-intensive, but they can be optimized using MongoDB's aggregation framework and other techniques to improve query performance.
How can you handle CORS to allow cookies to be included in requests?
- Access-Control-Allow-Origin: *
- Access-Control-Allow-Credentials: true
- Access-Control-Allow-Headers: *
- Access-Control-Allow-Methods: GET, POST
To allow cookies to be included in CORS requests, you should set the Access-Control-Allow-Credentials header to true. The other options are related to different aspects of CORS, but they don't specifically enable cookie handling.
What is the primary use of the spread operator in JavaScript?
- To merge arrays and objects
- To create a new array with the same elements
- To create a deep copy of an object
- To remove elements from an array
The primary use of the spread operator (...) in JavaScript is to merge arrays and objects. It can also be used to clone an array or object, effectively creating a new array or object with the same elements or properties.
How can you handle error responses in Express for cleaner error reporting?
- Using the throw statement
- Using the try...catch block
- Implementing custom error handling middleware
- Ignoring errors for cleaner logs
To handle error responses in Express for cleaner error reporting, you can implement custom error handling middleware. This middleware can catch errors and provide a standardized way to handle and respond to them, improving error reporting and debugging.
In Node.js, a buffer can be converted to JSON using the ______ method.
- toJSON
- bufferToJSON
- JSON.stringify
- serialize
To convert a buffer to JSON in Node.js, you can use the JSON.stringify method. This method will create a JSON string representation of the buffer's contents.
How can you ensure the reliability of your tests in a scenario where external services have inconsistent behavior?
- Mock the external services to simulate consistent behavior; Use retry mechanisms in your tests to account for inconsistencies; Write tests that ignore external services.
- Rely on external services' behavior as is, without any mitigation; Run the tests at a specific time when external services are expected to be consistent; Ignore testing external services.
- Always use real external services in your tests to ensure accuracy; Write tests that fail gracefully when external services are inconsistent; Run tests with random intervals to catch inconsistencies.
- Use external services only for integration tests, not unit tests; Write tests that expect failures due to external services; Use only internal services to avoid inconsistencies.
To ensure test reliability when external services have inconsistent behavior, it's best to mock the external services to simulate consistent behavior during tests. The other options either ignore the issue or rely on unpredictable external behavior.