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.
The method '______' is used to read data from a readable stream in Node.js.
- readData
- fetch
- read
- getData
In Node.js, the read method is used to read data from a readable stream. It allows you to retrieve data from the stream in chunks. The other options are not the correct methods for reading data from readable streams.
To run multiple npm scripts sequentially in the specified order, you can use npm run ______.
- series
- sequence
- concat
- parallel
To run multiple npm scripts sequentially, you can use the npm run command followed by the script names separated by space. The scripts will run in the order you specify, one after the other.
Cache ______ is a situation where multiple requests are made to a resource that is expensive to produce, causing a surge in load.
- Throttling
- Bursting
- Collapsing
- Overloading
Cache bursting is a situation where multiple requests are made to a resource that is expensive to produce, causing a surge in load. It typically occurs when cached data expires or when the cache is invalidated.
How can you create a custom lifecycle event that runs a series of npm scripts in a specified order?
- Use the pre and post prefixes with custom script names
- Use a third-party package like "npm-run-all"
- It's not possible to create custom lifecycle events
- Use JavaScript code within package.json
You can create a custom lifecycle event that runs a series of npm scripts in a specified order by using a third-party package like "npm-run-all." This package allows you to define complex run scripts in a convenient way, specifying the order of execution and handling dependencies between scripts.
How can you simulate user actions like clicks or keyboard inputs in Jest?
- jest.spyOn()
- jest.mock()
- jest.fn()
- jest.simulate()
In Jest, you can simulate user actions like clicks or keyboard inputs using jest.fn(). This allows you to create mock functions that can simulate user interactions and track their calls. The other options have different purposes; jest.spyOn() is used to spy on method calls, jest.mock() is used to mock modules, and jest.simulate() is not a valid Jest method for simulating user actions.
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.