How do dynamic imports affect the performance of a web application?
- Increase Performance
- Decrease Performance
- No Impact
- Depends on Implementation
Dynamic Imports can potentially decrease the initial load time of a web application by loading modules asynchronously. This can lead to improved performance, especially in scenarios where not all modules are required immediately. However, the actual impact depends on various factors, such as network conditions and how dynamic imports are implemented.
What happens when an iterator's next() method returns an object with done: true?
- It means the iteration is complete, and further calls to next() will throw an error
- It indicates an error in the iteration process
- It signals an infinite loop in the iteration
- It signifies that there are more elements to be iterated
When the next() method returns an object with done set to true, it indicates that the iteration has reached its end, and there are no more elements to be processed. Subsequent calls to next() will continue to return objects with done: true, providing a clear signal that the iteration is complete.
What is the correct syntax to create an instance of a class in ES6?
- let obj = new Class();
- let obj = create(Class);
- let obj = Object.create(Class);
- let obj = Class.create();
The correct syntax to create an instance of a class in ES6 is to use the new keyword followed by the class name and parentheses, like this: let obj = new Class();. The new keyword is essential for creating instances and invoking the class constructor.
In ES6, how is a method defined inside a class?
- Using the function keyword
- Using the method keyword
- Using the def keyword
- Using the => arrow syntax
In ES6, methods inside a class are defined using the => arrow syntax. This syntax provides a concise and cleaner way to declare methods within class definitions. It binds the method to the instance, allowing easy access to the class properties.
To handle errors within a generator function, the _________ method can be used alongside next().
- throw
- catch
- try
- finally
To handle errors in a generator function, the throw method can be used alongside the next() method. When an error is thrown, it is caught by the nearest catch block, allowing for graceful error handling within the generator.
What is the significance of the "exports" field in package.json for an ES6 module?
- Specifies the files to be exported
- Defines the entry point of the module
- Lists the dependencies for the module
- Indicates the module's public API
The "exports" field in package.json is significant for an ES6 module as it defines the module's public API. It specifies which parts of the module can be accessed by other modules when imported. This helps in controlling the visibility of internal implementation details.
In a web application that requires real-time data updates, how would the choice between Promises and callbacks affect performance and user experience?
- Promises may offer better performance due to their asynchronous nature
- Callbacks are preferable for real-time updates
- There's no significant impact on performance or user experience
- Promises introduce delays in real-time updates
In a web application requiring real-time data updates, choosing Promises may lead to better performance. Promises operate asynchronously, allowing non-blocking execution and potentially improving responsiveness. Callbacks, on the other hand, might result in callback hell and may not provide the same level of performance as Promises in handling real-time updates.
When using fetch, convert the response to JSON inside a try block and handle errors in ________.
- catch block
- then block
- finally block
- parse block
When fetching data with the 'fetch' API, it's advisable to convert the response to JSON inside a try block to handle successful responses and catch block to handle errors.
How does a for...of loop differ from a for...in loop in terms of iteration?
- for...of is used for arrays and iterable objects
- for...in is used for arrays and iterable objects
- for...of iterates over property values
- for...in iterates over property names
The for...of loop is designed specifically for iterating over values of iterable objects, such as arrays, while the for...in loop iterates over property names and is not limited to iterable objects.
In a scenario where an application needs to make several API calls and only proceed after all have successfully completed, what Promise method would be most appropriate?
- Promise.race
- Promise.all
- Promise.resolve
- Promise.reject
When dealing with multiple asynchronous operations, Promise.all is used to wait for all promises to be resolved. It ensures that the application proceeds only when all the promises are successfully completed, making it suitable for scenarios where multiple API calls need to be made concurrently.