ES6

Question 1

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

Answer 1

In JavaScript, codeblocks are denoted by { } containing statements, ie(functions, conditionals, loops)

Question 2

What does block scope mean?

Answer 2

the variable/declaration only exists within the block

Question 3

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

Answer 3

block-scoped

Question 4

What is the difference between let and const?

Answer 4

let can be reassigned, const cannot

Question 5

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

Answer 5

the const reference cannot be changed, but the value can

Question 6

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

Answer 6

const should be used if possible, use let if variables have to be reassigned values

Question 7

What is the syntax for writing a template literal?

Answer 7

same as regular strings except contained with backticks ( ` ), escape characters must be used if backticks are present in string ( /` ), no escape characters needed to go onto the next line either, just press enter

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

converting items in arrays/objects to single variables

Question 10

What is the syntax for Object destructuring?

Answer 10

let { property1: variable1, property2: variable2 } = object;

Question 11

What is the syntax for Array destructuring?

Answer 11

let [x,y,z] = [1,2,3]

Question 12

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

Answer 12

Objects include the property key and are in curly braces while arrays are in square braces

Question 13

What is the syntax for defining an arrow function?

Answer 13

without block syntax, no return needs to be specified
(parameters) => returnvalue
with block syntax:
(parameters) => {return returnvalue}

Question 14

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

Answer 14

you can only have one statement and you don’t need a return statement (implicit return)

Question 15

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

Answer 15

captures the this value of the enclosing context instead of creating its own this context

Question 16

What is a CLI?

Answer 16

command-line interface (interacts w applications via text)

Question 17

What is a GUI?

Answer 17

graphical user interface

Question 18

Give at least one use case for each of the commands listed in this exercise.
man
cat
ls
pwd
echo
touch
mkdir
mv
rm
cp

Answer 18

man - find out more about another command
cat - combine txt files
ls - list contents in a directory
pwd - check what directory you are in
echo - create txt document
touch - update access timestamps and create files if nonexisting
mkdir - create directory
mv - rename files
rm - remove files
cp - copy files/directories

Question 19

What are the three great virtues of a great programmer?

Answer 19

laziness, impatience, hubris

Question 20

What are the three states a Promise can be in?

Answer 20

pending, fulfilled, rejected

Question 21

How do you handle the fulfillment of a Promise?

Answer 21

variablename.then(value => { } );

‘then’ method plus function

Question 22

How do you handle the rejection of a Promise?

Answer 22

variablename.catch(error => { } );

‘catch’ method plus function

OR defining a second function in the .then method

Question 23

What is “syntactic sugar”?

Answer 23

syntax designed to make things easier to express/read

Question 24

What is the typeof an ES6 class?

Answer 24

function

Question 25

Describe ES6 class syntax.

Answer 25

class className {
     constructor(parameters) {
     }
     function(){
     }
}

Question 26

What is “refactoring”?

Answer 26

restructuring existing code to improve design/structure or implement new tech without changing the external behavior

Question 27

How are ES Modules different from CommonJS modules?

Answer 27

different syntax, commonJS is not part of the actual language - its part of node

Question 28

What kind of modules can Webpack support?

Answer 28

ECMAScript modules, CommonJS modules, AMD modules, Assets, WebAssembly modules