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.
Using _________, you can condense an array into a single value, optionally starting with an initial value.
- map
- reduce
- filter
- forEach
The correct answer is reduce. This method allows you to condense the elements of an array into a single value, using a provided function. It is particularly useful for tasks like summing values or finding the maximum element.
Asynchronous callbacks are placed in a queue known as the __________ queue.
- Callback Queue
- Event Queue
- Promise Queue
- Execution Queue
Asynchronous callbacks are placed in the Callback Queue, and they wait for the Event Loop to move them to the Call Stack for execution when the stack is empty.
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.
How are escape sequences like n treated in template literals?
- Treated as a newline character
- Ignored
- Treated as a literal backslash followed by 'n'
- Throws an error
In template literals, escape sequences like n are treated as newline characters. This allows for multi-line strings without the need for explicit line break characters.
In what order are tasks executed given JavaScript’s event loop and call stack mechanism?
- Based on the complexity of the task
- First In, First Out (FIFO) order
- Random order
- Last In, First Out (LIFO) order
Tasks in JavaScript are executed in a First In, First Out (FIFO) order. The event loop continually checks the call stack and executes tasks in the queue. This order ensures that tasks are processed in the sequence they are received, maintaining the integrity of the program's logic.
In a scenario where you need to convert an array of user objects into an array of names, which array method is the most suitable?
- map
- filter
- reduce
- forEach
In this scenario, the most suitable array method is map. The map method is designed for transforming each element of an array and returning a new array with the transformed values. It allows you to extract the names from the user objects efficiently.