Node.js

Question 1

What is Node.js?

Answer 1

A program that allows JavaScript to run outside of a web browser.

Question 2

What can Node.js be used for?

Answer 2

For creating the backend for web applications, writing command line programs, or some kind of automation.

Question 3

What is a REPL?

Answer 3

Read-Eval-Print Loop (REPL) is an environment that takes single user inputs, executes them, and returns the results.

Question 4

When was Node.js created?

Answer 4

2009.

Question 5

What back end languages have you heard of?

Answer 5

JS, PHP, Ruby Python Lua
C#, F#, Visual Basic
Java, Kotlin, Clojure Groovy

Question 6

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

Answer 6

It provides information about the current Node.js process.

Question 7

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

Answer 7

Calling the log method of the console object with one argument, the ‘process’ variable.

Question 8

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

Answer 8

An array (of strings).

Question 9

What is a JavaScript module?

Answer 9

A single .js file.

Question 10

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

Answer 10

__dirname, __filename, exports, module, require.

Question 11

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

Answer 11

process and console.

Question 12

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

Answer 12

To allow it’s information to be accessed by other Node.js modules.

Question 13

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

Answer 13

The require() function with a (string) parameter of the relative path of another Node.js module.

Question 14

What is the JavaScript Event Loop?

Answer 14

It waits for tasks and executes them. If there are no tasks, then it “sleeps” until it receives another task.

It looks at the stack and task queue. If the stack is empty, it takes the first thing on the task queue and puts it on the stack (and runs it).

Question 15

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

Answer 15

“Blocking” is executing code that prevents other code from executing until it is finished (“slow” or synchronous).

“Non-Blocking” is code that allows other code to execute while it is preparing itself to execute (“fast” or asynchronous).

Question 16

What is a directory?

Answer 16

A structure of folders that also reference other folders.

Question 17

What is a relative file path?

Answer 17

Shows how to get from the current working directory to the target file.

Question 18

What is an absolute file path?

Answer 18

Shows how to get from the root directory to the target file.

Question 19

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

Answer 19

The File System or ‘fs’ module.

Question 20

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

Answer 20

The .writeFile() method.

Question 21

Are file operations using the fs module synchronous or asynchronous?

Answer 21

fs. …Sync methods are synchronous.

fs.readFile() and fs.writeFile() are asynchronous.

Question 22

What is a client?

Answer 22

A computer that accesses a service(s) provided by a server.

Question 23

What is a server?

Answer 23

A computer provides a service(s) to one or more clients.

Question 24

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

Answer 24

The GET method.

Question 25

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

Answer 25

The HTTP method (i.e., GET, PUT, POST, etc.) followed by a resource URL.

Question 26

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

Answer 26

The protocol version (i.e., HTTP/1.1) followed by the status code and status code meaning.

Question 27

What are HTTP headers?

Answer 27

They allow the client and the server pass additional information with an HTTP request or response.

Question 28

Is a body required for a valid HTTP message?

Answer 28

No because not all responses have one.

Question 29

What is NPM?

Answer 29

(Node Package Manager) Allows a developers to share code that other developers can reuse in their own applications. NPM consists of the website, software registry, and CLI.

Question 30

What is a package?

Answer 30

A directory (sometimes called modules) with one or more files in it including a file called package.json. The file contains meta data about the package.

Question 31

How can you create a package.json with npm?

Answer 31

Using the ‘npm init (–yes)’ command.

Question 32

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

Answer 32

Other packages that are needed for a package to work. They can be added by using the ‘npm install’ command.

Question 33

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

Answer 33

Downloads the dependency to the local directory and updates the package.json file to include the dependency.

Question 34

How do you add express to your package dependencies?

Answer 34

The ‘npm install express’ command.

Question 35

What Express application method starts the server and binds it to a network PORT?

Answer 35

The .listen() method.

“Listening”: Waiting for a request.

Question 36

How do you mount a middleware the an Express application?

Answer 36

The .use() method with a parameter of a callback function with parameters, req and res.

When the server receives a request, what do you want to do?

Question 37

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

Answer 37

The req (HTTP request message - data model) object, res (HTTP response message - control) object, and the next object.

Question 38

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

Answer 38

‘application/json’

Question 39

What is the significance of an HTTP request’s method?

Answer 39

Allows the developer to decide what to do in response. It also determines the type of response is sent back to the client.

Semantics only. Expresses the intent of the client.

Question 40

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

Answer 40

It parses incoming JSON requests and stores it in req.body as an object.

Only need it when expecting clients to send the server JSON bodies.

Question 41

What is Webpack?

Answer 41

Webpack bundles JavaScript modules into a single output file that can be used in the frontend.

Question 42

How do you add a devDependency to a package?

Answer 42

npm install –save-dev (name of package)

Question 43

What is an NPM script?

Answer 43

NPM scripts are used to automate tasks.

A Command Line command with a nickname (property).

Question 44

How do you execute Webpack with npm run?

Answer 44

npm run

Question 45

What does express.static() return?

Answer 45

A function.

Question 46

What is the local __dirname variable in a Node.js module?

Answer 46

It stores the value of the directory name of the current module as a string.

Question 47

What does the join() method of Node’s path module do?

Answer 47

It combines the arguments into a single string separated by a forward slash.