JavaScript ES6+ Features

Assess your grasp of modern JavaScript syntax and features.

1. Which ES6 keyword is used to declare block-scoped variables that cannot be reassigned?

var let const

2. Which of the following are characteristics of arrow functions in ES6?

Shorter syntax than traditional function expressions Binds its own 'this' context Has an 'arguments' object Cannot be used as a constructor

3. Template literals in ES6 use backticks (`) for string interpolation.

True False

4. What is the abbreviation for the ES6 feature that spreads elements of an iterable into arrays or function arguments?

5. Which ES6 feature allows extracting values from arrays or objects into distinct variables?

Destructuring assignment Spread operator Rest parameter Template literals

6. Which of the following are part of ES6 module syntax?

import export require module.exports

7. The 'async/await' syntax was introduced in ES6 (2015).

True False

8. What is the output of `[1, 2, 3].map(x => x * 2)`?

9. In ES6, how do you set a default value for a function parameter?

function foo(x = 5) {} function foo(x: 5) {} function foo(x == 5) {} function foo(x || 5) {}

10. Which of the following are valid features of ES6 classes?

Constructor method Extends keyword for inheritance Private methods (using # syntax) Static methods

11. The rest parameter syntax (...) collects remaining function arguments into an array.

True False

12. What keyword is used to create a subclass that inherits from a parent class in ES6?

13. Which method is used to handle the successful resolution of a Promise in ES6?

.then() .catch() .finally() .resolve()

14. Which limitations apply to arrow functions in ES6?

Cannot be used as constructors (with 'new') No prototype property Cannot be used as generator functions (with '*') Can access 'super' keyword

15. ES6 introduced the 'Set' data structure, which stores unique values.

True False

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