To handle multiple Promises concurrently and respond when the first one is fulfilled, use Promise._________.
- all()
- race()
- any()
- first()
The correct method is race(). It returns a promise that fulfills or rejects as soon as one of the promises in the iterable fulfills or rejects, with the value or reason from that promise. This is useful for handling scenarios where you want to respond to the first promise that resolves.
How does a Set object handle NaN values?
- NaN is not allowed in a Set.
- It treats all NaN values as equal.
- Each NaN value is treated as a unique value in the Set.
- It throws an error when trying to add NaN.
Sets treat NaN values as equal. Therefore, adding multiple NaN values to a Set will result in having only one NaN value in the Set.
Imagine a data processing module that requires several steps of data validation and transformation. How can functional composition and currying simplify this process?
- Enhancing Readability and Reducing Code Duplication
- Increasing Code Complexity and Maintenance
- Decreasing Modularity and Reusability
- Streamlining Error Handling and Debugging
Functional composition allows creating separate functions for each step of data processing, promoting modularity and reusability. Currying enhances this process by breaking down each step into smaller, composable functions. This results in a more readable, maintainable, and error-resistant data processing module. The combined use of functional composition and currying simplifies the entire data processing workflow and improves the overall efficiency of the system.
How does the static method Promise.all() work with multiple promises?
- Executes all promises in parallel and returns a single promise that resolves when all promises are fulfilled or rejects when any promise is rejected.
- Executes promises sequentially and returns the result of the last promise.
- Randomly selects one promise to execute and returns its result.
- Executes promises concurrently but returns the result of the first fulfilled promise.
The Promise.all() method takes an array of promises, executes them in parallel, and returns a single promise that resolves when all the input promises have fulfilled or rejects when any one of them is rejected. This is useful for coordinating multiple asynchronous operations.
To import a default export, use import ______ from 'module-name';.
- defaultImport
- importDefault
- importDefaultExport
- importDefaultModule
In ES6, when importing a default export from a module, you use the syntax import name from 'module-name';. The keyword default is not used, making option b) importDefault the correct choice.
How can the spread operator be used to create a shallow copy of an object in ES6?
- Object.assign({}, originalObject)
- originalObject.clone()
- originalObject.spread()
- Object.copy(originalObject)
The spread operator (...) can be used to create a shallow copy of an object by spreading its properties into a new object literal. Object.assign({}, originalObject) is a common pattern for creating a shallow copy in ES6.
Can ES6 class methods be used as constructors for creating new objects?
- Yes, any class method can be used as a constructor
- No, only the constructor method can be used as a constructor
- Yes, but only static methods can be used as constructors
- No, ES6 classes cannot be used to create new objects
In ES6 classes, only the constructor method can be used as a constructor to initialize new objects. Other methods, including static methods, are not used for object instantiation.
In a game, how would a static method be used to keep track of the total number of players created across all instances of the player class?
- Use an instance method and increment a player counter in each instance.
- Create a global variable to store the total number of players and update it in the player constructor.
- Implement a static method that increments a static counter in the player class.
- Utilize a separate counter class and delegate the counting task to it.
To keep track of the total number of players created across all instances in a game, a static method within the player class is suitable. This static method can maintain a static counter, ensuring it's shared among all instances and doesn't rely on the state of a specific player instance. Using a global variable may lead to scope-related issues and is less modular.
When developing an application with multiple dependent asynchronous API calls, would you choose Promises or callbacks? Explain why.
- Use Promises
- Use callbacks
- It depends on the specific requirements
- Combine Promises and callbacks
In modern JavaScript development, using Promises is a preferred choice for handling multiple dependent asynchronous API calls. Promises provide a cleaner and more readable syntax, making it easier to manage asynchronous code. Promises also allow for better error handling through the use of .catch() and can be easily chained, improving code maintainability.
What syntax is used to handle the promise returned by a dynamic import?
- await import('module')
- import('module').then()
- dynamicImport('module')
- import('module').catch()
The correct syntax to handle the promise returned by a dynamic import is import('module').then(). You use the then method to perform actions once the module has been successfully loaded. The catch method can be used for error handling if the dynamic import fails.