What considerations should be made when handling JSON data in the response of a Fetch API call with Promises?
- Parsing JSON should be done using the .json() method.
- Directly using responseText is the preferred method.
- JSON handling is automatic; no considerations needed.
- JSON parsing is not supported in Promises.
When handling JSON data in a Fetch API call, it's crucial to use the .json() method to parse the response properly. This method returns a promise that resolves with the result of parsing the body text as JSON, ensuring proper handling of JSON data.
How can you create a custom iterable object using ES6 classes?
- Implement a next method with iterator protocol
- Use the Iterable interface
- Add a getIterator method
- Set the isIterable property to true
In ES6, custom iterable objects are created by implementing the next method with the iterator protocol. This method should return an object with the value and done properties. This allows the object to be iterated using a for...of loop.
How does 'this' behave within a static method?
- Refers to the instance calling the static method
- Refers to the class itself
- Points to the prototype of the class
- Is undefined
Within a static method, 'this' refers to the class itself, not an instance. This is because static methods are called on the class, not on instances, and they operate on class-level functionality. Therefore, 'this' inside a static method points to the class constructor, allowing access to static properties and methods.
Currying in JavaScript can help in creating functions that are ________ to specific scenarios.
- General
- Flexible
- Limited
- Specialized
Currying in JavaScript can help in creating functions that are specialized to specific scenarios. Currying is a technique where a function with multiple arguments is transformed into a series of functions, each taking a single argument. This enables creating more specialized functions tailored to specific use cases.
Using __________ at the beginning of an async function can help catch synchronous errors.
- try/catch
- await
- throw
- catch
Placing a try/catch block at the beginning of an async function allows you to catch and handle synchronous errors within the asynchronous context. This is important for comprehensive error handling in asynchronous code.
When using fetch to make an HTTP request, how do you ensure that HTTP errors are caught?
- response.ok
- response.status
- catch
- handleError
To catch HTTP errors when using the fetch API, you can use the catch method. This method is chained to the Promise returned by fetch and allows you to handle network errors, as well as HTTP errors (e.g., 404 or 500). By providing a callback function to catch, you can manage and respond to errors that may occur during the request.
When an async function throws an error and it is not caught, it results in a rejected __________.
- Promise
- Error
- Exception
- Rejection
When an async function throws an unhandled error, it results in a rejected Promise. The rejection carries the error information, and if not caught using a catch block or try...catch, it can lead to unhandled promise rejections. Understanding this behavior is essential for effective error handling in asynchronous code. Properly handling promise rejections ensures that errors are appropriately addressed, preventing unintended consequences in the application.
Composition in ES6 involves creating objects by combining multiple __________ that provide functionality.
- Promises
- Objects
- Prototypes
- Modules
Composition in ES6 involves creating objects by combining multiple objects that provide functionality. This promotes a modular and reusable code structure by assembling smaller pieces to form more complex objects.
Can default parameters be expressions or function calls?
- No, only primitive values are allowed
- Yes, any valid expression or function call is allowed
- Only function calls are allowed
- Only arrow function expressions are allowed
Yes, default parameters in ES6 can be expressions or function calls. This enables dynamic default values based on the evaluation of expressions or the result of function calls. It provides flexibility and allows for more sophisticated default values in function parameters.
Can a static method in a parent class be overridden in a child class?
- Yes
- No
- Depends on the method implementation
- Only if explicitly declared as override
Yes, a static method in a parent class can be overridden in a child class. However, it's important to note that static methods are associated with the class itself rather than instances, and the child class can provide its own implementation of the static method, effectively overriding the one in the parent class.
In Node.js, ES6 Modules have a different file extension (_________) compared to CommonJS modules (.js).
- .mjs
- .es6
- .es
- .node
Node.js uses the .mjs file extension for ES6 modules to differentiate them from CommonJS modules that typically use the .js extension. This helps Node.js to identify the module type and apply the appropriate module loading mechanism.
In object methods, using arrow functions can lead to issues when relying on the this keyword, as it does not bind its own this, but inherits it from the ________ scope.
- Parent
- Global
- Lexical
- Block
Arrow functions inherit the this value from their lexical scope, which means the scope in which they were defined. This can lead to unexpected behavior when used in object methods.