In ES6, what happens when the spread operator is used with an iterable like a string?
- Spreads each character into an array
- Concatenates the string
- Reverses the string
- Throws an error
When the spread operator (...) is used with an iterable like a string, it spreads each character of the string into an array. This allows you to easily convert a string into an array of characters in ES6.
What is the main difference between a mixin and a class in ES6?
- Mixins are Objects
- Classes can have Constructors
- Mixins support Inheritance
- Classes support Composition
The main difference lies in their approach to code structuring. Classes in ES6 follow a classical inheritance model with constructors, while mixins are essentially objects that provide specific functionalities. Mixins promote composition, allowing the combination of features from various sources, while classes are more focused on defining and instantiating objects with a specific structure.
Can generator functions be used to implement asynchronous operations in JavaScript?
- Yes
- No
- Only in modern browsers
- Only in Node.js
Yes, generator functions can be used to implement asynchronous operations using concepts like cooperative multitasking and promises. By yielding promises and handling them appropriately, asynchronous code can be written in a more synchronous style, improving readability and maintainability.
How can the spread operator facilitate the process of adding elements to state arrays in a React component without mutating the original state?
- Create a new array using the spread operator, add elements, and set the state
- Use the Array.push() method to add elements to the state array
- Directly modify the existing state array
- Utilize the Array.concat() method to add elements to the state array
The spread operator is used in React to avoid mutating the state directly. Creating a new array with the spread operator, adding elements, and then setting the state ensures immutability and proper state management in React components.
Can you define currying in JavaScript?
- A technique of transforming a function with multiple arguments into a sequence of functions
- A method to manipulate arrays in JavaScript
- A way to create objects using constructors
- An approach to handling asynchronous code
Currying is a technique in JavaScript that involves transforming a function with multiple arguments into a sequence of functions, each taking a single argument. This allows for partial application of the function, making it more flexible and reusable. Currying is particularly useful in functional programming and can lead to more concise and modular code. A solid understanding of currying is beneficial for developers working with JavaScript.
Dynamic imports return a __________ which resolves to the module.
- Promise
- Object
- Function
- String
Dynamic imports in JavaScript return a Promise, which resolves to the module. This asynchronous approach allows for the dynamic loading of modules, enhancing the efficiency of the application by loading resources only when needed. The Promise returned by the dynamic import can be further utilized to handle the module after it has been successfully loaded. Understanding this concept is crucial for efficient code splitting and optimizing performance in JavaScript applications.
Is it possible to dynamically import modules using ES6 syntax, and how does it differ for named and default exports?
- Yes, the syntax is the same for both
- Yes, but the syntax differs
- No, dynamic imports are not supported in ES6
- Only named exports can be dynamically imported
It is possible to dynamically import modules using ES6 syntax. The syntax is the same for both named and default exports, providing a dynamic way to load modules when needed. The key difference lies in how the imported values are accessed in the code.
The ES6 __________ syntax in object literals allows for creating properties with the same name as local variables.
- Rest
- Spread
- Destructuring
- Arrow
In ES6, the destructuring syntax in object literals allows for creating properties with the same name as local variables. It provides a concise way to extract values from objects and arrays.
Consider a module that exports multiple utility functions. How would you import a specific function for optimizing bundle size?
- Importing the entire module and using the specific utility function
- Destructuring the import statement to only include the needed utility function
- Importing the module dynamically at runtime based on the required utility function
- Using a wildcard import to import all utility functions
To optimize bundle size, it's advisable to import only the specific utility function needed rather than importing the entire module. Destructuring the import statement allows you to selectively import only the required function, reducing unnecessary code and improving performance.
To prevent infinite recursion, it is important to define a __________ that stops the recursion.
- Base case
- Recursive case
- Break statement
- Counter variable
In recursive functions, a base case is crucial to terminate the recursion. It is the condition that, when met, stops the function from calling itself endlessly.