ES6 Basics

1/25 Constants are block-scoped variables.
- True
- False
2/25 What will the result of the following be?
```
const speed = 'quick'; `The ${speed} brown fox jumps over the lazy dog.`
```
- SyntaxError
- "The speed brown fox jumps over the lazy dog."
- "The quick brown fox jumps over the lazy dog."
- Undefined
- The `quick` brown fox jumps over the lazy dog.
3/25 String interpolation is a much-needed new feature that is finally available in JavaScript. See the example below. Is there anything wrong with it?
```
let name = 'Harry';

let occupation = 'wizard';

console.log(`Hi! My name is ${name}. I'm a ${occupation}.`);
```
- Nothing wrong with the example. This is how the feature works in ES6.
- The example is wrong. You can't break a String into lines in JavaScript.
- The example is wrong. You can't embed variables in String in JavaScript.
- None of the above.
4/25 What value will this expression return?
```
let x, { x: y = 1 } = { x };   y;
```
- { x: 1 }
- 1
- { x : 1 }
- "undefined"
5/25 What is a Promise()?
- Tool for managing asynchronous control flow. A promise represents an operation expected to complete in the future.
- The opposite of Amateurmise().
- Something you say, when you want someone to believe you.
- None of the above.
6/25 What value will this expression return?
```
[...[...'...']].length
```
- 3
- 6
- 9
- Error
7/25 What will the result of this expression be?
```
typeof (new (class F extends (String, Array) { })).substring
```
- Error
- "undefined"
- "object"
- "function"

8/25 What will this function return?

(function() { 

if (false) {

 let f = { g() => 1 };

 }

 return typeof f;

 })()

Undefined
"object"
"function"
Error

9/25 Why is super used?
- Is used for creating and initializing an object.
- It's a simple function.
- Is used as an "object" which calls the parent class.
- Is used as a "function" which calls the parent's constructor.
10/25 ES6 gives an alternative way to assign variables. Can you guess what the below code does?
```
let a = 12, b = 3;

[a, b] = [b, a];
```
- Makes both a and b equal 12.
- Swaps the values inside a and b, without using extra variables.
- Creates an array that contains a and b.
11/25 Which method introduced in ES6 is used to merge two or more arrays?
- Array.join()
- Array.concat()
- Array.merge()
- Array.combine()
12/25 What is the main purpose of the spread operator in ES6?
- To spread objects into arrays
- To expand iterable objects into individual elements
- To combine multiple functions into one
- To spread arrays into objects
13/25 Which ES6 feature provides a new way to handle asynchronous operations?
- Callbacks
- Promises
- Async/Await
- Event Listeners
14/25 What does the 'Set' object introduced in ES6 represent?
- A collection of unique values
- A key-value map
- A sequential list of elements
- A set of functions
15/25 Which ES6 feature allows for declaring read-only named constants?
- let
- var
- const
- static
16/25 Which ES6 feature is used to write expressions in a more concise way?
- Arrow Functions
- Template Literals
- Promises
- Destructuring Assignment
17/25 How does 'const' behave differently from 'var' in ES6?
- const variables can be reassigned
- const creates block-level scope
- const does not allow hoisting
- const is not compatible with older browsers
18/25 What is the main advantage of using 'let' over 'var' in ES6?
- let provides function scope
- let supports redeclaration in the same scope
- let provides block-level scope
- let improves performance
19/25 In ES6, which statement correctly imports a single export from a module?
- import { myExport }
- import myExport from 'module'
- require('module').myExport
- load myExport from 'module'
20/25 How does the 'for...of' loop in ES6 differ from 'for...in'?
- for...of iterates over properties
- for...of is used for objects
- for...of iterates over iterable objects like arrays
- There is no difference
21/25 What ES6 feature provides a shorthand syntax for assigning properties to variables of the same name?
- Property Shorthand
- Object Destructuring
- Variable Initialization
- Arrow Functions
22/25 In ES6, what is the purpose of 'WeakSet'?
- To store a weakly held set of unique values
- To create a set with weakened security
- To store a set of weak references
- To create a less efficient version of Set
23/25 How does 'yield' work in ES6?
- It pauses and resumes a generator function
- It yields control to another function
- It produces a value from a sequence
- It generates random values
24/25 What is the main feature of 'Async/Await' introduced in ES8 (ECMAScript 2017)?
- Synchronous programming
- Error handling
- Asynchronous programming
- Parallel processing
25/25 In ES6, what does 'Object.is()' do?
- Checks if two values are the same value
- Checks if an object has a specific property
- Creates a new object
- Compares two objects deeply
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ES6 Basics

1/25 Constants are block-scoped variables.

2/25 What will the result of the following be?

3/25 String interpolation is a much-needed new feature that is finally available in JavaScript. See the example below. Is there anything wrong with it?

4/25 What value will this expression return?

5/25 What is a Promise()?

6/25 What value will this expression return?

7/25 What will the result of this expression be?

8/25 What will this function return?

9/25 Why is super used?

10/25 ES6 gives an alternative way to assign variables. Can you guess what the below code does?

11/25 Which method introduced in ES6 is used to merge two or more arrays?

12/25 What is the main purpose of the spread operator in ES6?

13/25 Which ES6 feature provides a new way to handle asynchronous operations?

14/25 What does the 'Set' object introduced in ES6 represent?

15/25 Which ES6 feature allows for declaring read-only named constants?

16/25 Which ES6 feature is used to write expressions in a more concise way?

17/25 How does 'const' behave differently from 'var' in ES6?

18/25 What is the main advantage of using 'let' over 'var' in ES6?

19/25 In ES6, which statement correctly imports a single export from a module?

20/25 How does the 'for...of' loop in ES6 differ from 'for...in'?

21/25 What ES6 feature provides a shorthand syntax for assigning properties to variables of the same name?

22/25 In ES6, what is the purpose of 'WeakSet'?

23/25 How does 'yield' work in ES6?

24/25 What is the main feature of 'Async/Await' introduced in ES8 (ECMAScript 2017)?

25/25 In ES6, what does 'Object.is()' do?