Node

Question 1

pwd

Answer 1

print the current directory you in

where am I

Question 2

echo

Answer 2

print content

console.log

Question 3

touch

Answer 3

access time of the last edit time of the file

Question 4

ls ‘xxx’

Answer 4

list directory contents
xxx: target directory

Question 5

mkdir

Answer 5

create directory

Question 6

mv

Answer 6

rename directory or file

Question 7

rm

Answer 7

delete file only or use -r

Question 8

cp

Answer 8

copy files or directories

Question 9

rmdir

Answer 9

delete directory

Question 10

What is a CLI?

Answer 10

command line interface

Question 11

What is a GUI?

Answer 11

graphacial user interface

Question 12

man

Answer 12

an interface to the system reference manuals

Question 13

cat

Answer 13

concatenate files and print on the standard output

print the content of files

Question 14

ls

Answer 14

list directory contents

Question 15

What is Node.js?

Answer 15

Node.js 是能够在服务器端运行JavaScript 的开放源代码、跨平台执行环境。

Question 16

What can Node.js be used for?

Answer 16

It is used for server-side programming, and primarily deployed for non-blocking, event-driven servers, such as traditional web sites and back-end API services, but was originally designed with real-time, push-based architectures in mind.

Question 17

What is a REPL?

Answer 17

Read–eval–print loop)
“读取-求值-输出”循环，也被称做交互式顶层构件，是一个简单的，交互式的编程环境。这个词常常用于指代一个Lisp的交互式开发环境，也能指代命令行的模式。

Question 18

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

Answer 18

data model of

Question 19

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

Answer 19

just reference it

Question 20

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

Answer 20

array of strings

Question 21

What is a JavaScript module?

Answer 21

module is the file with code

Question 22

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

Answer 22

exports, require, module, __filename, __dirname

Question 23

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

Answer 23

process, global

Question 24

What is the purpose of module.exports in a Node.js module?

Answer 24

make it available to other modual

Question 25

How do you import functionality into a Node.js module from another Node.js module?

Answer 25

call require with () require here is a reference (or a copy) of module.export.

Question 26

What is the JavaScript Event Loop?

Answer 26

the event loop is the part of a JS runtime environment, that pushes asynchronous callback onto the callstack when callstack is clear

Question 27

What is different between "blocking" and "non-blocking" with respect to how code is executed?

Answer 27

Blocking refers to operations that block further execution until that operation finishes while non-blocking refers to code that doesn't block execution. block (synchronous): this code will processed first , after it processed , rest code can be executed (ex: loop) non-block (asynchronous): this code will processed, while it is processing , rest code can be executed too. (ex: HTTP request AJAX)

Question 28

What is a directory?

Answer 28

list of files

Question 29

What is a relative file path?

Answer 29

get from where you are to where you want to go

Question 30

What is an absolute file path?

Answer 30

location of file from root directory

Question 31

What module does Node.js include for manipulating the file system?

Answer 31

fs module

Question 32

What method is available in the Node.js fs module for writing data to a file?

Answer 32

fs.writeFile

Question 33

Are file operations using the fs module synchronous or asynchronous?

Question 34

What is a client?

Answer 34

a program send request to server

Question 35

What is a server?

Answer 35

a server send request back to user

Question 36

Which HTTP method does a browser issue to a web server when you visit a URL?

Answer 36

GET

Question 37

What is on the first line of an HTTP request message?

Answer 37

GET request-target(the thing you ask server for, if it's / means give me whatever you have) HTTP/1.1 (format)

Question 38

curl

Answer 38

just like httpie bur less functional , build in every computer. curl=see url

Question 39

What is on the first line of an HTTP response message?

Answer 39

protocol message , code, status

Question 40

What are HTTP headers?

Answer 40

extra info, just like head of html elements

Question 41

Is a body required for a valid HTTP message?

Answer 41

no

Question 42

domain name system

Answer 42

a bunch of servers that loop up IP address for domains, they also remember them for a while (like a phone book, when you got the URL ex.amazon.com, it will look for the IP of this website)

Question 43

nc

Answer 43

make internet connect and catch all the stuff

Question 44

what is behind the webpage url(domain name)

Answer 44

ip address. each website have different ip addresses

Question 45

http port?

Answer 45

Default in http is 80 in https is 443 (drive to a restaurant , window you can order and perform actions)

Question 46

What is NPM

Answer 46

website, registration list, cml Registration have pacgages you can download by using cml

Question 47

How can you create a package.json with npm?

Answer 47

npm init --yes

Question 48

What is a dependency and how to you add one to a package?

Answer 48

dependency: modules from npm how to add: npm install xxx

Question 49

What happens when you add a dependency to a package with npm?

Answer 49

the package.json is updated with the new dependency and the package is downloaded from the npm registry to node_modules

Question 50

What is a package?

Answer 50

modules create by others and published on npm

Question 51

Which objects does an Express application pass to your middleware to manage the request/response lifecycle of the server?

Answer 51

req, res

Question 52

How do you mount a middleware with an Express application?

Answer 52

use()

Question 53

address().port

Answer 53

shows the port number

Question 54

What is the appropriate Content-Type header for HTTP messages that contain JSON in their bodies?

Answer 54

application/json

Question 55

What does the express.json() middleware do and when would you need it?

Question 56

app.delete('/api/grades/:id', (req, res) =>{}

Answer 56

:id is a placeholder

Question 57

What are some advantages of learning a relational database?

Question 58

What is PostgreSQL and what are some alternative relational databases?

Answer 58

widely use

Question 59

What is one way to see if PostgreSQL is running?

Answer 59

sudo service postgresql status

Question 60

What is a database schema?

Answer 60

schema define structure

Question 60

What is a database schema?

Answer 60

schema define structure of datas

Question 61

What is a table?

Answer 61

list of rows have same attribute

Question 62

What is a row?

Answer 62

the data