ES6 Interview Questions and Answers for 2 years experience

0
ES6 Interview Questions and Answers

  1. What are arrow functions and how do they differ from regular functions?

    • Answer: Arrow functions provide a shorter syntax for writing functions. Key differences include: they don't have their own `this` binding (inherit `this` from the surrounding scope), they cannot be used as constructors, and they don't have arguments object. They are best suited for short, concise functions.

  2. Explain the concept of `let` and `const` in ES6.

    • Answer: `let` declares block-scoped variables, meaning their scope is limited to the block, statement, or expression they are defined within. `const` declares block-scoped variables that are also read-only. Once assigned a value, they cannot be reassigned. However, if `const` refers to an object or array, the properties or elements of that object/array can still be modified.

  3. What are template literals? Give an example.

    • Answer: Template literals use backticks (`) to define strings, allowing embedded expressions using ${expression}. Example: `let name = "John"; console.log(`Hello, ${name}!`);`

  4. Describe destructuring in ES6. Provide examples for arrays and objects.

    • Answer: Destructuring allows assigning values from arrays or objects to distinct variables in a concise way. Array example: `let [a, b] = [1, 2];` Object example: `let {name, age} = {name: "Jane", age: 30};`

  5. What is the spread syntax (...) and how is it used?

    • Answer: The spread syntax allows expanding iterable objects (arrays, strings, maps, sets) into individual elements. It's used for copying arrays, combining arrays, and passing array elements as function arguments.

  6. Explain the rest parameter syntax (...).

    • Answer: The rest parameter syntax allows a function to accept an indefinite number of arguments as an array. `function sum(...numbers) { return numbers.reduce((a, b) => a + b, 0); }`

  7. What are default parameters in ES6 functions?

    • Answer: Default parameters provide default values for function parameters if no value is passed during the function call. `function greet(name = "Guest") { console.log(`Hello, ${name}!`); }`

  8. How do you use `import` and `export` for modules in ES6?

    • Answer: `export` is used in a module to make variables, functions, or classes available for use in other modules. `import` is used in another module to access the exported elements. Example: `export const PI = 3.14159;` (in moduleA.js) and `import { PI } from './moduleA.js';` (in moduleB.js)

  9. Explain classes in ES6. How do they differ from prototypal inheritance?

    • Answer: ES6 classes provide syntactic sugar over JavaScript's prototypal inheritance. They offer a cleaner and more familiar syntax for creating objects and handling inheritance, but fundamentally operate on the same underlying prototypal inheritance mechanism.

  10. What are Promises in ES6? Explain their states and how to handle them using `.then()` and `.catch()`.

    • Answer: Promises represent the eventual result of an asynchronous operation. They have three states: pending, fulfilled (resolved), and rejected. `.then()` is used to handle the fulfilled state, while `.catch()` handles the rejected state.

  11. What is `async/await` and how does it simplify asynchronous code?

    • Answer: `async/await` provides a more synchronous-looking way to write asynchronous code using Promises. `async` declares an asynchronous function, and `await` pauses execution until a Promise is resolved.

  12. What are Sets in ES6? What are their key features?

    • Answer: Sets are collections of unique values. Key features include adding, deleting, checking for existence of elements, and iterating through the unique elements.

  13. What are Maps in ES6? How do they differ from Objects?

    • Answer: Maps are collections of key-value pairs where keys can be of any data type, not just strings like in Objects. They also provide methods for efficient iteration and size checking.

  14. Explain Symbols in ES6. What are their use cases?

    • Answer: Symbols are unique and immutable values. They are often used to create unique object properties that are less likely to collide with other properties.

  15. What are iterators and generators in ES6?

    • Answer: Iterators provide a standard way to traverse data structures. Generators are a special type of function that can pause execution and resume later, yielding values one at a time. They are useful for creating custom iterators.

  16. Explain the concept of Proxies in ES6.

    • Answer: Proxies allow intercepting and customizing operations performed on an object. This is useful for things like data validation, logging, or creating virtual objects.

Thank you for reading our blog post on 'ES6 Interview Questions and Answers for 2 years experience'.We hope you found it informative and useful.Stay tuned for more insightful content!