ES6 JS

Question 1

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

Answer 1

A code block is a line of code within curly braces such as after an if statement, function call/function definition css ruleset, loop conditionals

Question 2

What does block scope mean?

Answer 2

It means that within a code block that would be the block scope. if the block scope is local then it pertains to inside the curly braces other wise global means the whole js file.

Question 3

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

Answer 3

both are block scoped and read-only, the content is immutable where as let, if an object can change reference data.

Question 4

What is the difference between let and const?

Answer 4

Const cannot be reassigned, variable declared by let are mutable so the values can change, const needs to be initialized.

Question 5

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

Answer 5

The array can add elements it does not change the value. however because it is const it cannot be reassigned as it is immutable

Question 6

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

Answer 6

if u do not wish to reassign values to the variable use const, within for loops use let unless it is a for..of loop then use const.

Question 7

What is the syntax for writing a template literal?

Answer 7

` ` - using back ticks,

${variable_name } - use this syntax to substitute a variable within it

Question 8

What is “string interpolation”?

Answer 8

It is when a a template literal has substitutions and string

Question 9

What is destructuring, conceptually?

Answer 9

Taking properties from an object or values from an array and creating individual variables.

Question 10

What is the syntax for Object destructuring?

Answer 10

let person = {
firstName: DJ
}

THIS IS THE SYNTAX: let {firstName} = person;
or const{(propertyName:(name of variable u choose)} = person; both will have different
You have a keyword either let, const, or var within an object literal

Question 11

What is the syntax for Array destructuring?

Answer 11

it is a keyword let, const, or var followed by array literal and then intialized to an array.
Ex: const array = [1,2,3]
 const [num1, num2, num 3] = array;

console.log(num1) is 1;

Question 12

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

Answer 12

Creating object/array means it is on the right side of the assignment operator

Destructuring means it is the keyword let, const, var followed by object/array literal and then whatever is being assigned to that

CREATE: const person = [ ] || { };

Destructuring: const {you} || [you] = [ ] || { };

Question 13

What is the syntax for defining an arrow function?

Answer 13

It will be parameter followed by arrow then code 
let variable_name = () => some code;

Question 14

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

Answer 14

It does not need the return key word after the arrow

Question 15

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

Answer 15

It inherits this from the function it is in.

Question 16

WHAT IS CLI?

Answer 16

CommandLine InterFace

Question 17

What is GUI?

Answer 17

Graphical User Interface, The user can move and interact with it

Question 18

Give at least one USE case for each
man
cat
ls
pwd
echo
touch
mkdir
mv
rm
cp

Answer 18

man - manual for each command line tool
cat - prints the content of file
ls - looks at the directories list
pwd -Prints the working directory can create files within the pwd
echo - can put whats printed on CLI in a file
touch - gives a time stamp
mkdir - can make a new directory or more than one
mv - used to change a file name or move file
rm - can delete files
cp - copy the contents of one file into another one

Question 19

what is Node.js

Answer 19

It lets javascript run outside of the browser

Question 20

What can Node.js be used for?

Answer 20

It can be used to run javascript within the terminal, command line tools

Question 21

What is a REPL?

Answer 21

read-eval-print loop gives programmers interactive programming envrionment

Question 22

When was Node.js created?

Answer 22

2009

Question 23

What back end languages have you heard of?

Answer 23

Python, Ruby, SQL

Question 24

What is a computer process?

Answer 24

It is the process of threads that the computer runs

Question 25

Roughly how many computer processes are running on your host operating system (Task Manager or Activity Monitor)?

Answer 25

over 500

Question 26

Why should a full stack Web developer know that computer processes exist?

Answer 26

So that they can understand memory space and such

Question 27

What is the process object in a Node.js program?

Answer 27

The process object is a global that provides information about, and control over, the current Node.js process. As a global, it is always available to Node.js applications without using require(). It can also be explicitly accessed using require():

Question 28

How do you access the process object in a Node.js program?

Answer 28

Can access by console logging or using the process object in a js file.

Question 29

What is the data type of process.argv in Node.js?

Answer 29

it is an array data type

Question 30

What is a JavaScript module?

Answer 30

it is a file with some type of functionality that will other modules creates a cohesive functional app

Question 31

What values are passed into a Node.js module’s local scope?

Answer 31

exports require module __filename, __dirname

Question 32

Give two examples of truly global variables in a Node.js program.

Answer 32

Console and process

Question 33

What is Array.prototype.filter useful for?

Answer 33

It is useful for getting indexes using a specific criteria

Question 34

What is Array.prototype.map useful for?

Answer 34

It is useful for changing all indexes of an array without having to use a for loop

data transformation - the same legnth

Question 35

what is array.prototype.reduce useful for?

Answer 35

It is useful for having a single output from an array.

Question 36

What is “syntactic sugar”?

Answer 36

It is when making code easier to read or to express while keeping functionality

Question 37

What is the typeof an ES6 class?

Answer 37

It is an function

Question 38

Describe ES6 class syntax.

Answer 38

Syntax as follows:

class (constructor Name) {

  constructor (parameter) {
        this.parameter = parameter
    }
    getP() {
          return this.parameter
      } 
}

Question 39

what is refactoring?

Answer 39

it is cleaning up the readability of code to be more concise without the functionality being changed, improves performance.

Question 40

What is a webpack?

Answer 40

It is script files concatenated into one big file

Question 41

How do you add a devDependency to a package?

Answer 41

when using npm install –save-dev (script name)

Question 42

What is an NPM script?

Answer 42

a code or file that will run continuously, or calling the script will run the file

Question 43

How do you execute Webpack with npm run?

Answer 43

use npm run and then the script name or build

Question 44

How are ES Modules different from CommonJS modules?

Answer 44

They use different syntaxes as ES6 modules use imports and exports statements where as commonJs uses module.exports and requireJS

Question 45

What kind of modules can Webpack support?

Answer 45

It supports both kind of modules

Question 46

what does fetch() return?

Answer 46

A Promise that resolves to a Response object.

Question 47

What is the default request method used by fetch()?

Answer 47

GET

Question 48

How do you specify the request method (GET, POST, etc.) when calling fetch

Answer 48

fetch (url, { method: 'POST' 
body: ,
headers: 
});
.then(response => response.json());