Node.js Flashcards
What makes Node.js good as a runtime environment?
It is non-blocking, which means it can handle concurrent connections efficiently
What does GET do, is it safe and can it be cached?
GET retrieves data from the server, it is safe as it does not have any side effects on the server and it can be cached
What does POST do? Is it safe and is it cached?
Used to submit data to be processed by the server, it is not safe as it may have side effects of the server and they are not cached
What does PUT do?
Used to update a resource on the server, it may require additional security considerations.
What does PUT being idempotent entail?
Multiple identical requests will produce the same result as a single one
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How to import the http module?
const http = require(“http”);
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How to create a server?
const server = http.createServer();
server.listen(port);
server.listen(3000, () => {console.log(…);}); to check functionality
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The configuration of a createServer()
const server = http.createServer((req, res) => {console.log(“res”)});
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How to send response from server?
res.write(“Response”);
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How to finish response?
res.end();
How to send Header in server?
res.writeHead(200, {“Content type” : “text/plain”});
What pieces can be parsed from the following URL:
http://site.com/path/?q=val#hash
In order:
site.com hostname
/path/ pathname
q=val query
#hash hash
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How to implement routes for different HTTP methods? Write some statements accordingly
We use the req.method
if (req.method===”GET”){
res.writeHead(200, {“Content type” : “text/plain”});
res.end(“GET method used”);
}
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The two required statements to parse request data
const url = require(“url”);
const querystring = require(“querystring”);
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Given the required modules, how to parse a URL?
const parsedURL = url.parse(req.url);
const queryParams = querystring.parse(parsedURL.query);
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How to import express.js
const express = require(“express”);
const app = express();
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How to handle routes with express
const express = require(“express”);
const app = express();
app.post(“action”, (req, res) => {res.send(“…”);});
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How to file I/O?
const fs = require(“fs”);
fs.writeFile(“fileToWriteTo.txt”, “Written Text”);
fs.readFile(“fileToReadFrom.txt”);
What does path.join() do?
What module does it require?
It constructs a valid file path, from various parts of file paths.
const path = require(“path”), also requires express
What is __dirname?
It represents the directory of the current module, where the script is located
What does express.static? What does it do?
It is middleware employed to serve static files. It also makes files in the “public” directory static resources, meaning they are available to clients.
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The statements required for static file handling (the required modules and the code)
const express = require(“express”);
const app = express();
const path = require(“path”);
app.use(express.static(path.join(__dirname, “public”)));
What are cookies (simplest definition)?
Small pieces of data stored on the client’s browser.
What is the purpose of cookies?
They store information that is accessible across different pages/sessions (user preferences, tracking user behavior, etc…)
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How to implement the cookieParser?
const express = require(“express”);
const app = “express”
const cookieParser = require(“cookie-parser”);
app.use(cookieParser());
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How to set a cookie?
app.get(“/set-cookie”, (req, res) => {
res.cookie(“username”, “Lud”);
res.end(“Cookie is set”);});
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How to read a cookie?
req.cookies.property
What are sessions?
A mechanism for maintaining user state across multiple requests, they are stored on the server
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How to use express-session middleware?
const express = require(“express”);
const session = require(“express-session”);
const app = express();
app.use(session({
secret: “your-secret-key”;}));
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How to set a session?
app.get(“/set-session”, (req, res) => {
req.session.username(“Dave”);
res.send(“username set”);});
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How to get a session?
app.get(“/get-session”, (req, res) => { const username = req.session.username;
res.send(“Hello, ${username}”);});
