When chaining promises, the return value of one .then() becomes the input for the next _________.
- catch()
- resolve()
- reject()
- then()
The correct term is then(). When chaining promises, the then() method is used to specify what should happen next after the Promise is fulfilled. The value returned by the then() callback becomes the input for the next then() in the chain.
When using const with destructuring, you must provide a _________ at the time of declaration.
- Value
- Reference
- Type
- Default Value
When using const with destructuring, you must provide a value at the time of declaration. This is because, once a variable is declared with const, you cannot reassign it later.
Can await be used inside a regular (non-async) function?
- No, it can only be used in async functions
- Yes, it can be used to make any function asynchronous
- Yes, but it will result in a runtime error
- No, it is only applicable in arrow functions
The await keyword can only be used inside functions marked with the async keyword. Attempting to use await in a regular function will result in a syntax error.
In ES6, which scenario would necessitate using let over const?
- When the variable needs to be reassigned
- When the variable should remain constant throughout its scope
- When the variable is used in a loop
- When the variable is a function declaration
The 'let' keyword should be used when the variable needs to be reassigned within its scope, as 'const' variables cannot be reassigned after initialization. 'const' is appropriate for variables that should remain constant throughout their scope.
When implementing a function to make API requests, how would you structure it to effectively handle both network errors and incorrect responses?
- Returning an error object for network errors and throwing an exception for incorrect responses
- Using separate callback functions for network errors and incorrect responses
- Combining network errors and incorrect responses into a single error object
- Utilizing a single callback function with different error codes for network and response issues
By returning an error object for network errors and throwing an exception for incorrect responses, the function can communicate distinct issues. This approach ensures a clear separation between network-related errors and issues with the API response, allowing for better identification and handling of specific problems. Separate callback functions or combining errors into a single object may lead to ambiguity in error handling.
How are mixins typically applied to a class in ES6?
- Using the extends keyword
- Using the include keyword
- Using the mixin keyword
- By manually copying and pasting the code
Mixins are typically applied to a class in ES6 using the extends keyword. This establishes a relationship between the class and the mixin, allowing the class to inherit the properties and methods defined in the mixin. This method of composition is clean and maintains a clear structure in the code.
In a logging function, how can default parameters be used to control the verbosity of the logs?
- Set a default verbosity level, and users can adjust it by providing an optional parameter, like log(message, verbosity = 1).
- Use default parameters to enable users to specify different levels of verbosity, such as log(message, level = "info").
- Allow users to pass a verbosity parameter and use default parameters to handle cases where no verbosity level is provided.
- Implement default parameters for both message and verbosity, allowing users to adjust verbosity while still logging a default message.
Default parameters can be employed in a logging function to control the verbosity of the logs. By setting a default verbosity level, users can choose to override it when calling the function, providing flexibility in controlling the amount of detail in the logs. It simplifies the logging function's usage while still offering customization based on the user's needs.
Q2: If you are managing a group of user objects, each with associated metadata, how would using a WeakMap affect memory management compared to using a Map?
- WeakMap
- Map
- Both WeakMap and Map
- Neither WeakMap nor Map
Using a WeakMap for managing user objects with associated metadata is advantageous for memory management. In a WeakMap, keys are weakly referenced, meaning that if there are no other references to a key, it can be garbage collected. This is useful when managing user objects because if a user object is removed elsewhere in the application, the associated metadata can also be automatically cleared from the WeakMap, preventing unnecessary memory consumption. A Map, on the other hand, would retain the user objects in memory even if they are no longer needed, potentially leading to memory issues.
In destructuring assignment, _________ can be used to gather the rest of the elements/properties into a new array or object.
- Spread operator
- Rest operator
- Concatenation operator
- Merge operator
In destructuring assignment, the correct option is the "Rest operator." The rest operator allows you to gather the remaining elements or properties into a new array or object, making it a powerful tool for working with structured data. It is denoted by three dots (...).
In a recursive function, the _________ parameter can be used to accumulate results across calls.
- Accumulator
- Recursive
- Accumulation
- Result
In-depth content in the explanation. The accumulator parameter in a recursive function is used to accumulate and store results across multiple recursive calls. It helps maintain a running total or aggregate information during the recursion process.