Imagine designing a class hierarchy for vehicles. How would you use constructors and the super keyword when creating a class for a specific type of vehicle, like a truck?
- Utilize the constructor to initialize specific properties and use super to call the parent class constructor.
- Ignore constructors and super, relying on default values for properties.
- Use only the super keyword without constructors for simplicity.
- Use constructors but avoid the super keyword for vehicle class creation.
In designing a class hierarchy, the constructor is crucial to initialize specific properties of the truck class. The super keyword ensures that the parent class constructor is called, setting up common attributes shared among all vehicles. This promotes code reusability and a clear inheritance structure.
In a subclass constructor, the super keyword must be called before accessing _______.
- parent properties
- child properties
- subclass properties
- constructor properties
In a subclass constructor, the super keyword must be called before accessing parent properties. This is because the super keyword refers to the parent class, and it needs to be invoked first to ensure that the parent's properties are properly initialized before accessing them in the subclass.
In a web application, how would you efficiently load multiple resources in parallel using async/await?
- Load resources using Promise.all
- Use Promise.race for parallel loading
- Sequentially load each resource using await
- Utilize a combination of Promise.all and async/await
In an asynchronous context, Promise.all is used to efficiently load multiple resources in parallel. It allows for concurrent execution of promises and is commonly used with async/await to enhance code readability and maintainability.
In ES6, can a class extend more than one class at a time?
- Yes
- No
- Only if the classes have a common ancestor
- Only in certain scenarios
In ES6, a class can extend only one other class at a time. Unlike some other programming languages that support multiple inheritance, JavaScript (ES6) does not allow a class to directly extend more than one class. This design choice helps avoid complications related to ambiguity and conflicts that may arise with multiple inheritance.
What are the first and second arguments of a tag function in a tagged template literal?
- The template string and an array containing the evaluated expressions.
- The evaluated expressions and the template string.
- The tag function itself and the template string.
- The template string and the number of expressions.
In a tagged template literal, the tag function is called with the template string as the first argument and an array containing the evaluated expressions as the second argument. This enables customized processing of the template and its expressions.
Using rest parameters alongside default parameters can result in more concise and flexible function definitions.
- Spread Operators
- Arrow Functions
- Template Literals
- Destructuring Assignment
In JavaScript, rest parameters (...) allow a function to accept an indefinite number of arguments as an array. Combining rest parameters with default parameters enables the creation of more versatile and compact functions. The spread operator, which is the correct option, is used to collect function arguments as an array.
When using a for...of loop, what keyword is used to access the current item in the collection?
- for
- in
- of
- each
The for...of loop uses the "of" keyword to iterate over the values of an iterable object, providing a cleaner syntax compared to the for...in loop.
In ES6, a function parameter's default value can be another function's _________.
- name
- return value
- parameters
- scope
In ES6, a function parameter's default value can be another function's return value. This allows for dynamic default values based on the execution of the provided function.
In what scenario would a callback be more appropriate than a Promise?
- When dealing with simple and sequential asynchronous tasks.
- Callbacks are never more appropriate than Promises.
- In complex situations where multiple asynchronous tasks depend on each other.
- Promises are always preferred over callbacks.
Callbacks are suitable for straightforward, sequential tasks where the asynchronous nature is not overly complex. Promises shine in scenarios involving more complex asynchronous workflows, providing better control and readability. Understanding the use cases for callbacks versus Promises is essential for choosing the right approach in different asynchronous programming scenarios.
When designing a library for UI components, how would the use of ES6 classes and inheritance improve the code structure and reusability?
- Prototype Chain
- Object Literal Notation
- Composition over Inheritance
- Extending Base Components
By using ES6 classes and inheritance, you can create a hierarchy of UI components, making it easier to manage shared functionality and customize specific components. Options A and B are not directly related to ES6 classes, and Option C emphasizes composition as a preferred pattern.
How do getter and setter methods in ES6 classes enhance object property access?
- They allow direct modification of private properties
- They enable the use of arrow functions
- They provide a way to control access to object properties
- They are only used for static properties
In ES6 classes, getter and setter methods allow controlled access to object properties. Getters retrieve the value, and setters modify the value, providing a way to implement data validation or custom behavior during property access or modification.
The spread operator is used to ________ elements of an iterable into individual elements.
- Combine
- Separate
- Flatten
- Merge
The spread operator (...) is used to separate the elements of an iterable, like an array, into individual elements. This is often used to spread elements into a new array or function arguments.