Node.js Flashcards
What is Node.js?
allows you to do js outside of the browser
What can Node.js be used for?
build and launch apps from your computer
What is a REPL?
read eval print loop that allows you to input commands, execute them, and return results
When was Node.js created?
2009?
What back end languages have you heard of?
C++ python C ruby go javascript java
What is a computer process?
it is an instance of a computer program that is being executed by one or many threads
Roughly how many computer processes are running on your host operating system?
6 apps running, 132 background processes
Why should a full stack web developer know that computer processes exist?
know what sort of burden you are putting on a computer with your app
What is the process object in a Node.js program?
The projcess 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()
How do you access the process object in a Node.js program?
You can access it by using console logging it or you can access it’s children by index
it is global so you can access it whenever
What is the data type of process.argv in Node.js?
array of strings
What is a JS module?
a simple part of a more complex, larger system
a file within many files for js
What values are passed into a Node.js module’s local scope?
exports, require, module, __filename, __dirname
Give two examples of truly global variables in a Node.js program
process console
What is the purpose of module.exports in a Node.js module?
move code between files
How do you import functionality into a Node.js module from another Node.js module?
use require
What is the JavaScript Event Loop?
it is essentially a a queue of commands that are waiting to be run after the call stack has been filled and emptied
What is different between “blocking” and “non-blocking” with respect to how code is executed?
blocking is essentially code that is synchronous while nonblocking is code that is asynchronous
What is a directory?
a folder
What is a relative file path?
the url of a file that is relative to the url of the file that you are using
What is an absolute file path?
the absolute file path is the exact route of the file in question
What module does Node.js include for manipulating the file system?
fs
What method is available in the Node.js fs module for writing data to a file?
fs.writeFile
Are file operations using the fs module synchronous or asynchronous?
both
What is NPM?
it stands for node package manager and it is a software registry where you can share packages
What is a package?
packages are reusable code, and are sometimes called modules
a package.json file:
- lists the packages your project depends on
- specifies versions of a package that your project can use using semantic versioning rules
- makes your build reproducible, and therefore easier to share with other developers
How can you create a package.json with npm?
make sure that you are in your root directory and you need to run npm init
to make a default package.json using information extracted from the current directory, use the npm init command with the –yes or -y flag
What is a dependency and how do you add one to a package?
this is a package that your code depends on; when you run npm install, npm will download dependencies and devDependencies that are listed in package.json that meet the semantic version requirements listed for each
What happens when you add a dependency to a package with npm?
it gets added to the node-modules directory that is either in your directory or newly created, and it is listed as a dependency in the package.json file
How do you add express to your package dependencies?
npm install express
What Express application method starts the server and binds it to a network PORT?
listen
How do you mount a middleware with an Express application?
use method
Which objects does an Express application pass to your middleware to manage the request/response lifecycle of the server?
request and response
What is the appropriate Content-Type header for HTTP messages that contain JSON in their bodies?
application/json
