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.
How does chaining array methods like map and filter affect performance?
- Negatively impacts performance due to multiple iterations
- Positively impacts performance by optimizing the code
- No significant impact on performance
- Only affects readability, not performance
Chaining array methods like map and filter can negatively impact performance due to multiple iterations. Each method creates a new array, and chaining them leads to intermediate arrays, causing additional iterations. This can be inefficient, especially for large datasets.
Imagine processing a shopping cart array to calculate the total price. Which method would efficiently achieve this?
- map
- reduce
- filter
- forEach
The most efficient method for calculating the total price in a shopping cart array is reduce. The reduce method iterates over each element of the array and accumulates a result. In this case, it can sum up the prices to provide the total cost.
What is a practical use case of currying in JavaScript?
- Simplifying function composition
- Handling asynchronous operations
- Memoization
- Event handling in UI
Currying simplifies function composition by breaking down functions into smaller, reusable units. This is useful for creating more modular and maintainable code, especially in functional programming paradigms.
How can dynamic imports be used to implement feature flags in a large-scale web application?
- Load all features during the initial page load.
- Use dynamic imports to conditionally load features based on feature flags.
- Hardcode feature flags directly in the application code.
- Use static imports to include all features in the main bundle.
Dynamic imports enable the implementation of feature flags by allowing the loading of features based on runtime conditions. This flexibility helps in enabling or disabling specific features without changing the core codebase.
Can a default export be imported with any name?
- Yes
- No
- Only in certain cases
- Depends on the file structure
In ES6, a default export can be imported with any name. The imported name is not dictated by the exporting module. It allows flexibility in naming while importing, making it more convenient.