ES6 Basics

1/25 The statement "let" declares a block scope local variable.
- True
- False
2/25 What is the final value of "obj" in the following example?
```
const obj = { foo: 1 }; 
obj.bar = 2;
```
- { foo: 1 }
- { foo: 1, bar: 2 }
- { foo: 1, 2: bar }
- None of the above
3/25 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.
4/25 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.
5/25 ES6 gives you a number of new methods for operating with Strings. Which one replaces this annoying piece of code?
```
let some_text = "some string"; 
if(some_text.indexOf('str') !=-1){
 return true;
 }
```
- some_text.repeat('str');
- some_text.endsWith('str');
- some_text.includes('str');
6/25 Array.from() is a powerful method which converts array-like objects into real Arrays. Why do you use it in the code below?
```
let titleElements = document.querySelectorAll('.article .title') let titles = Array.from(titleElements).map( t => t.textContent ); console.log(titles);
```
- This code is wrong and won't work.
- You use it because it is hip.
- You need it, because querySelectorAll returns a NodeList, which doesn't have the map method, and only arrays do.
7/25 What is stored in the triangle array?
```
let point = [1,3], segment = [point,[5,5]], triangle = [...segment,[1,8]];
```
- 23
- [1,3,5,5,1,8]
- [ [1,3], [5,5], [1,8] ]

8/25 Is this a valid code?

class Slave { // ... };
 const slave = Slave();

9/25 Which statement about arrow functions in ES6 is true?
- They do not have their own 'this' context
- They can be used as constructors
- They are not hoisted
- They have their own 'arguments' object
10/25 Which ES6 feature provides a new way to handle asynchronous operations?
- Callbacks
- Promises
- Async/Await
- Event Listeners
11/25 In ES6, which keyword is used to import modules?
- require
- import
- include
- load
12/25 What is the output of the following code snippet? `const [a, , b] = [1, 2, 3]; console.log(a, b);`
```
const [a, , b] = [1, 2, 3]; 
console.log(a, b);
```
- 1, 2
- 2, 3
- 1, 3
- undefined, undefined
13/25 What is the result of using '...' in function parameters?
- Spread Operator
- Rest Parameters
- Destructuring
- Array Concatenation
14/25 Which new data structure introduced in ES6 stores unique values of any type?
- Array
- Object
- Map
- Set
15/25 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'
16/25 What is a 'Proxy' in ES6?
- A method for creating objects
- A way to handle asynchronous requests
- A type of function
- An object that wraps another object to control access to it
17/25 In ES6, what is the main use of a 'Symbol'?
- To create unique, immutable identifiers
- To symbolize constants
- To enhance security
- To replace strings
18/25 In ES6, which statement correctly creates a class that extends another class?
- class SubClass extends BaseClass {}
- class SubClass inherits BaseClass {}
- SubClass.prototype = new BaseClass();
- class SubClass: BaseClass {}
19/25 Which method in ES6 is used to copy an object?
- Object.copy()
- Object.clone()
- Object.assign()
- Object.duplicate()
20/25 What does the 'find' method do on an array in ES6?
- Finds and replaces elements
- Finds the first element satisfying a condition
- Finds all elements that match a condition
- Sorts the array
21/25 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
22/25 Which of the following is a new string method introduced in ES6?
- .contains()
- .includes()
- .findString()
- .hasText()
23/25 What is the main feature of 'Async/Await' introduced in ES8 (ECMAScript 2017)?
- Synchronous programming
- Error handling
- Asynchronous programming
- Parallel processing
24/25 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
25/25 How does the 'endsWith()' method work with ES6 strings?
- It checks if a string ends with a specified substring
- It appends a specified substring to the end of a string
- It removes the specified substring from the end of a string
- It capitalizes the final character of a string
To get the result of the quiz, please provide your email address (optional)..

It seems you haven't answered any questions yet. Please provide your answers to proceed.

ES6 Basics

1/25 The statement "let" declares a block scope local variable.

2/25 What is the final value of "obj" in the following example?

3/25 What will the result of the following be?

4/25 String interpolation is a much-needed new feature that is finally available in JavaScript. See the example below. Is there anything wrong with it?

5/25 ES6 gives you a number of new methods for operating with Strings. Which one replaces this annoying piece of code?

6/25 Array.from() is a powerful method which converts array-like objects into real Arrays. Why do you use it in the code below?

7/25 What is stored in the triangle array?

8/25 Is this a valid code?

9/25 Which statement about arrow functions in ES6 is true?

10/25 Which ES6 feature provides a new way to handle asynchronous operations?

11/25 In ES6, which keyword is used to import modules?

12/25 What is the output of the following code snippet? `const [a, , b] = [1, 2, 3]; console.log(a, b);`

13/25 What is the result of using '...' in function parameters?

14/25 Which new data structure introduced in ES6 stores unique values of any type?

15/25 In ES6, which statement correctly imports a single export from a module?

16/25 What is a 'Proxy' in ES6?

17/25 In ES6, what is the main use of a 'Symbol'?

18/25 In ES6, which statement correctly creates a class that extends another class?

19/25 Which method in ES6 is used to copy an object?

20/25 What does the 'find' method do on an array in ES6?

21/25 How does 'yield' work in ES6?

22/25 Which of the following is a new string method introduced in ES6?

23/25 What is the main feature of 'Async/Await' introduced in ES8 (ECMAScript 2017)?

24/25 In ES6, what does 'Object.is()' do?

25/25 How does the 'endsWith()' method work with ES6 strings?