Using a WeakMap for private data ensures that the data is garbage collected when the object key is no longer ________.
- Referenced
- Immutable
- Mutable
- Valid
When using a WeakMap for private data, the data is tied to the object key, and it will be garbage collected when the object is no longer referenced elsewhere in the code. This helps in managing memory efficiently for private data in JavaScript.
In a scenario where a function needs to access the this keyword of a containing object, should an arrow function be used?
- Yes, always
- No, never
- It depends
- Only in classes
Arrow functions should not be used in this scenario because they do not bind their own "this" and instead inherit it from the enclosing scope. This can lead to unintended behavior when trying to access the "this" keyword of a containing object.
In a scenario where a function receives a complex object as an argument, how can destructuring assignment enhance code readability and maintenance?
- It has no effect on code readability
- It makes code more complex
- It simplifies the extraction of values from the object
- It can only be used with primitive data types
When a function receives a complex object as an argument, using destructuring assignment can significantly enhance code readability and maintenance. By specifying the necessary properties directly in the function parameter, developers can easily understand which values the function expects. This not only simplifies the code but also reduces the need for repeated object property access, making the code more efficient and easier to maintain.
Consider a scenario where you are handling multiple independent API calls. How would the approach differ using Promises compared to callbacks?
- Promises allow for better parallel execution
- Callbacks are more suitable for independent calls
- Promises are slower for independent calls
- Callbacks lead to callback hell
When dealing with multiple independent API calls, Promises offer a significant advantage by allowing for better parallel execution. Unlike callbacks, which may result in nested structures (callback hell), Promises provide a more elegant solution through chaining, resulting in cleaner and more maintainable code.
Consider a function designed to format a date. How would you use default parameters to provide flexibility in the format?
- Utilize default parameters to allow users to specify the format, such as formatDate(date, format = "YYYY-MM-DD").
- Use default parameters for individual components like day, month, and year, enabling customization while maintaining a default format.
- Allow a default format but also accept an optional format parameter, giving users the ability to override the default if needed.
- Use default parameters to set a default format but allow users to pass a custom formatting function, giving maximum flexibility.
Default parameters in JavaScript allow you to assign default values to function parameters. In the context of formatting a date, default parameters can be used to provide a default format, and users can override this by passing their desired format as an argument. This provides a balance between having a predefined format and allowing customization based on user needs.
In ES6, how does the spread operator enhance the functionality of higher-order functions?
- Allows the spreading of elements in an array or properties in an object
- Facilitates the creation of closures within higher-order functions
- Enables the use of async/await syntax in functions
- Enhances the performance of recursion in functional programming
The spread operator in ES6 allows the spreading of elements in an array or properties in an object, making it useful for operations like array concatenation and object merging within higher-order functions.
What is the primary purpose of destructuring assignment in ES6?
- Simplifying the process of extracting values from arrays or objects
- Declaring variables in a concise manner
- Improving code readability by using shorthand syntax
- Allowing variables to be reassigned easily
Destructuring assignment in ES6 is primarily used to simplify the process of extracting values from arrays or objects, making code more concise and readable. It allows you to declare variables and assign values in a single line, improving code structure.
Which keyword is used to define a class in ES6?
- class
- type
- struct
- interface
In ES6, the class keyword is used to define a class. It provides a cleaner syntax for creating constructor functions and prototypes. Classes allow for easier code organization and inheritance in JavaScript.
A Symbol can be explicitly converted to a string using __________ method.
- toString()
- valueOf()
- convertToString()
- description()
The correct method to explicitly convert a Symbol to a string is toString(). The toString() method is a built-in method for Symbol instances, which returns the string representation of the Symbol.
When implementing a recursive function in ES6, what considerations should be made regarding stack overflow?
- Tail call optimization eliminates the risk of stack overflow in all cases.
- It's essential to handle base cases properly to avoid stack overflow.
- Stack overflow is unavoidable in recursive functions in ES6.
- Increasing the stack size is the only solution to prevent overflow.
When implementing recursive functions in ES6, it's crucial to handle base cases effectively to prevent stack overflow. While tail call optimization can help in some cases, it's not universally guaranteed, making proper base case management a fundamental consideration.