In ES6, what is the behavior of using super in a method when extending a class?
- Calls the superclass constructor
- References the superclass prototype
- Creates a new instance of the superclass
- Invokes the superclass method
In ES6, when using super in a method of a subclass, it refers to the superclass, allowing access to its methods and properties. It is often used to call the superclass constructor using super() or invoke methods on the superclass. This facilitates extending the functionality of the superclass.
What is the base case in a recursive function?
- The initial condition
- The stopping condition
- The recursive condition
- The iterative condition
In a recursive function, the base case is the condition that prevents further recursion. It is crucial for stopping the recursion and ensuring that the function does not enter an infinite loop.
In ES6, mixins can be created by a function that takes a _________ as an argument and extends it.
- Class
- Function
- Object
- Module
In ES6, mixins are created by a function that takes an object as an argument and extends it. This approach allows for dynamic composition, enabling the combination of functionalities from different sources into a single object.
What are the implications of using default parameters on function length property?
- The length property reflects the number of parameters without default values
- The length property includes parameters with default values
- Default parameters do not affect the length property
- The length property is no longer relevant with default parameters
When default parameters are used in a function, they do not contribute to the length property. The length property only counts the number of parameters without default values. Therefore, the length might not accurately represent the total number of arguments the function can accept.
Is it possible to destructure properties from nested objects?
- Yes
- No
- Only if the nested object has a single property
- Only if the nested object is declared as a constant
Yes, in ES6, destructuring assignment can be used to extract properties from nested objects. This allows for a more convenient and concise way of accessing values within nested structures, enhancing code simplicity.
A common use case for WeakMap is to store ________ data for objects.
- metadata
- private
- public
- static
A common use case for WeakMap is to store metadata or additional information related to objects. Since WeakMap does not prevent object keys from being garbage collected, it's useful for storing data that should not interfere with garbage collection.
Consider a scenario where you are integrating third-party APIs in a web application. How would you ensure that API failures do not crash your application?
- Implementing robust error handling, logging, and potentially using circuit breakers
- Ignoring API errors and allowing the application to continue execution
- Restarting the application upon API failure
- Redirecting users to a generic error page on any API failure
Ensuring the resilience of the application against API failures involves implementing robust error handling mechanisms. This includes catching and logging errors, implementing retry strategies, and potentially using circuit breakers to temporarily halt requests in the event of persistent failures. Ignoring errors or restarting the application can lead to a degraded user experience and make troubleshooting difficult.
When creating a utility class with common helper functions, how would you ensure that these methods are accessible without instantiating the class?
- Use static methods
- Use private methods
- Use public methods
- Use protected methods
In ES6, you can ensure that methods in a utility class are accessible without instantiating the class by defining them as static methods. Static methods are associated with the class itself rather than instances, allowing you to call them directly on the class without creating an object. This is beneficial for utility classes where instantiation is unnecessary, and you want to organize related functions.
Can you nest template literals within each other?
- Yes
- No
- Only if they have the same variables
- Only in arrow functions
Template literals can be nested within each other, allowing for more complex string constructions. This nesting can be useful when building strings that involve multiple layers of dynamic content.
Describe the flow of execution in a JavaScript program that includes both synchronous logging and asynchronous API calls.
- The synchronous code is executed first, followed by the asynchronous API call. The API call is offloaded to the browser's APIs, and its callback is queued in the task queue. Once the call stack is empty, the event loop picks up the callback, and its execution is prioritized.
- Synchronous logging occurs immediately in the call stack, while the asynchronous API call is offloaded to the browser's APIs. The event loop ensures the callback is queued and executed once the call stack is empty, allowing non-blocking behavior.
- The JavaScript program executes synchronous logging first, and then the asynchronous API call is delegated to the browser's APIs. The event loop monitors the call stack and task queue, ensuring the asynchronous callback is prioritized for execution.
- The event loop manages the asynchronous API call, queuing its callback, and ensuring it is executed once the call stack is empty. Synchronous logging happens directly in the call stack, maintaining a smooth flow of execution in the JavaScript program.
The flow of execution in a JavaScript program involves synchronous logging and asynchronous API calls. The synchronous code is executed first, followed by the asynchronous API call, which is offloaded to the browser's APIs. The event loop ensures that the callback is queued and prioritized for execution once the call stack is empty. Understanding this flow is essential for handling mixed synchronous and asynchronous operations effectively.