ES6 Basics

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

5/25 What will this function return?

(function() { 

if (false) {

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

 }

 return typeof f;

 })()

Undefined
"object"
"function"
Error

6/25 What result will this expression have?
```
typeof (function* f() { yield f })().next().next()
```
- "generator"
- "object"
- "function"
- Error
7/25 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');
8/25 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.

9/25 Is this a valid code?

class Slave { // ... };

 const slave = Slave();

10/25 Which method introduced in ES6 is used to merge two or more arrays?
- Array.join()
- Array.concat()
- Array.merge()
- Array.combine()
11/25 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
12/25 Which of the following is a template literal in ES6?
- 'Hello World'
- `Hello ${name}`
- "Hello " + name
- Hello + name
13/25 In ES6, which syntax is used for defining a class?
- function MyClass() {}
- class MyClass {}
- MyClass = new Class()
- object MyClass {}
14/25 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
15/25 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
16/25 In ES6, what is the main use of a 'Symbol'?
- To create unique, immutable identifiers
- To symbolize constants
- To enhance security
- To replace strings
17/25 What does the 'Map' object introduced in ES6 represent?
- A collection of key-value pairs
- A list of unique values
- A new way to create arrays
- A mapping function for arrays
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 is the result of using a template literal inside another template literal?
- Syntax error
- The inner template literal is ignored
- Nested template processing
- Automatic string conversion
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 The statement "let" declares a block scope local variable.

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 is a Promise()?

5/25 What will this function return?

6/25 What result will this expression have?

7/25 ES6 gives you a number of new methods for operating with Strings. Which one replaces this annoying piece of code?

8/25 ES6 gives an alternative way to assign variables. Can you guess what the below code does?

9/25 Is this a valid code?

10/25 Which method introduced in ES6 is used to merge two or more arrays?

11/25 Which statement about arrow functions in ES6 is true?

12/25 Which of the following is a template literal in ES6?

13/25 In ES6, which syntax is used for defining a class?

14/25 What is the main advantage of using 'let' over 'var' in ES6?

15/25 What is a 'Proxy' in ES6?

16/25 In ES6, what is the main use of a 'Symbol'?

17/25 What does the 'Map' object introduced in ES6 represent?

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 is the result of using a template literal inside another template literal?

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