ES6

Question 1

What is a code block? What are some examples of a code block?

Answer 1

Code blocks are denoted by culry braces { }

The show up in conditionals and functions.

Question 2

What does block scope mean?

Answer 2

It means that the var/let and its value is only effective within that code block that it is declared in.

Question 3

What is the scope of a variable declared with const or let?

Answer 3

they are block-scoped, as they are NOT global and cannot be accessed outside of the block they are contained in

Question 4

What is the difference between let and const?

Answer 4

const CANNOT be reassigned while let can be mutable

Question 5

Why is it possible to .push() a new value into a const variable that points to an Array?

Answer 5

Because you can still ADD values to the object, but you cannot reassign the value. So push() is fine, but

Question 6

How should you decide on which type of declaration to use?

Answer 6

Whether or not the variable needs to be reassigned or not. if it doesnt, then const would be the choice you should use.

Question 7

What is the syntax for writing a template literal?

Answer 7

let string = ` the text within the string `

instead of using quotes for strings, we are using backticks. This will let the user have multiline strings and be able to use any quotations freely’

Question 8

What is “string interpolation”?

Answer 8

The ability to substitute part of the string for the values of variables or expressions.

Question 9

What is destructuring, conceptually?

Answer 9

assigns the properties of an object to variables with the same names by default, unless stated otherwise.

Question 10

What is the syntax for Object destructuring?

Answer 10

let { object.property1, object.property2…. etc} = object.

Question 11

What is the syntax for Array destructuring?

Answer 11

let [x, y, z] = array.

This will set the variables of x, y, z to the first 3 indexes of the array.
If the array is < 3, the ‘empty’ variables will be undefined.
If the array is > (the # of listed variables), all argumenst AFTER the last listed variable will be disregarded.

it can use [x, y, … arg] to set all the values after y to another string.

Question 12

How can you tell the difference between destructuring and creating Object/Array literals?

Answer 12

object destructuring is mentioning the property the object that contains.
array destructuring only names the new variables that is ‘coming out’

Question 13

What is the syntax for defining an arrow function?

Answer 13

(x,y) =>

this states the parameters of the function and what the function is going to do

Question 14

When an arrow function’s body is left without curly braces, what changes in its functionality?

Answer 14

without curly braces, it can only use an expression.

WITH curly braces, you can use a statement and an expression.

Question 15

How is the value of this determined within an arrow function?

Answer 15

an arrow function captures the this value of the enclosing context instead of creating its own this context.

Question 16

What is “syntactic sugar”?

Answer 16

It is a type of syntax that is designed to make things easier to read or to express

Question 17

What is the typeof an ES6 class

Answer 17

it is a function

Question 18

Describe ES6 class syntax

Answer 18

you start with the ‘class’ keyword followed by ‘${name of function}’ {

class Student {
}

Question 19

What is “refactoring”

Answer 19

is the process of restructuring existing computer code- changing the factoring without changing its external behavior.

Question 20

How are ES Modules different from CommonJS modules?

Answer 20

they can be statically analyzed(for static checking,optimization, etc)

Their support for cyclic dependencies is better than common JS

Question 21

What kind of modules can Webpack support?

Answer 21

ECMAScript6 modules