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https://github.com/seogeurim/learnyounode
Solutions to the learnyounode tutorial
https://github.com/seogeurim/learnyounode
Last synced: 9 days ago
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Solutions to the learnyounode tutorial
- Host: GitHub
- URL: https://github.com/seogeurim/learnyounode
- Owner: Seogeurim
- Created: 2021-06-29T18:59:10.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2021-07-01T07:36:18.000Z (over 3 years ago)
- Last Synced: 2024-10-29T22:39:12.264Z (about 2 months ago)
- Language: JavaScript
- Size: 257 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# LearnYouNode
Node.js basic tutorial **learnyounode** from [NodeSchool](https://nodeschool.io/)
> [https://github.com/workshopper/learnyounode](https://github.com/workshopper/learnyounode)
## 01. HELLO WORLD [🔗](./hello-world.js)
> make Node.js program
### # execute program
- create a new file with a .js extension
- running it with the node command
```bash
$ node hello-world.js
```
## 02. BABY STEPS [🔗](./baby-steps.js)
> access command-line arguments
### # process object : argv property
- `process.argv` : an array containing the complete command-line
- all elements of `process.argv` are strings
```bash
$ node command-line-test.js 1 2 3
```
```js
console.log(process.argv); // ['node', '/path/to/your/command-line-test.js', '1', '2', '3']
```
## 03. MY FIRST I/O! [🔗](./my-first-io.js)
> synchronous filesystem operation
### # fs module
- Node core library
- all synchronous (or blocking) filesystem methods in the fs module end with `Sync`
- `fs.readFileSync('/path/to/file')` : read a file synchronous, returns a Buffer object
- supply `utf8` as the second argument : returns String instead of a Buffer
- Buffer objects can be converted to strings by calling the `toString()` method
## 04. MY FIRST ASYNC I/O! [🔗](./my-first-async-io.js)
> asynchronous filesystem operation
### # fs module - readFile
- `fs.readFile('/path/to/file', callback)` : read a file asynchronous
- callback signature : `function callback (err, data) { /* ... */ }`, `data` is a Buffer object
- supply `utf8` as the second argument and put the callback as the third argument : `data` is a String instead of a Buffer
## 05. FILTERED LS [🔗](./filtered-ls.js)
> list of files
### # fs module - readdir
- `fs.readdir('/path/to/dir', callback)` : read the contents of a directory asynchronous
- callback signature : `function callback (err, list) { /* ... */ }`, `list` is an array of filename strings
### # path module
- Node core library
- `extname` method : returns the extension of the path (ex. `.md`)
## 06. MAKE IT MODULAR [🔗](./make-it-modular.js)
> module system
### # create module
- to define a single function export : `module.exports = function (args) { /* ... */ }`
- to use new module : `const mymodule = require('./mymodule.js')`
## 07. HTTP CLIENT [🔗](./http-client.js)
> HTTP GET request
### # http module
- Node core library
- `http.get(url, callback)` : performs an HTTP GET request
- callback signature : `function callback (response) { /* ... */ }`, `response` object is a Node Stream object
- Node Stream
- emit events like `'data'`, `'error'`, `'end'` ... : `response.on('data', function (data) { /* ... */ })`
- has `setEncoding()` method : `response.setEncoding('utf-8')`
## 08. HTTP COLLECT [🔗](./http-collect.js)
> collect data across multiple events
### # bl(Buffer List) module / concat-stream module
- both have a stream piped in to them and will collect the data
- `response.pipe(bl(function (err, data) { /* ... */ }))`
- `response.pipe(concatStream(function (data) { /* ... */ }))`
- `data` is a Buffer object
## 09. JUGGLING ASYNC [🔗](./juggling-async.js)
> collect data from multiple URLs in sequence
### # more convenient
- [`async`](https://www.npmjs.com/package/async)
- [`run-parallel`](https://www.npmjs.com/package/run-parallel)
## 10. TIME SERVER [🔗](./time-server.js)
> write a TCP time server
### # net module
- Node core library
- `net.createServer(listener)` : create raw TCP server, returns an instance of server
- listener signature : `function listener (socket) { /* ... */ }`
- `socket` object : a Node duplex Stream, can be both read from and
written to
- `socket.write(data)` : write data to the socket
- `socket.end()` : close the socket
- `socket.end(data)` : write data and close the socket
- must call `server.listen(portNumber)` to start listening on a particular port
```js
/* A typical Node TCP server */
const net = require('net');
const server = net.createServer(function (socket) {
// socket handling logic
});
server.listen(8000);
```
### # create date - `new Date()` object
- `date.getFullYear()`
- `date.getMonth()` // starts at 0
- `date.getDate()` // returns the day of month
- `date.getHours()`
- `date.getMinutes()`
## 11. HTTP FILE SERVER [🔗](./http-file-server.js)
> HTTP server that serves file
### # http module - create server
- `http.createServer(callback)` : create an HTTP server, returns an instance of server
- callback signature : `function callback (request, response) { /* ... */ }`
- `request`, `response` : Node streams
- must call `server.listen(portNumber)` to start listening on a particular port
### # fs module - createReadStream
- `fs.createReadStream(file)` : create a stream representing the file, returns stream object
- `src.pipe(dst)` : pipe the data from the `src` stream to the `dst` stream
## 12. HTTP UPPERCASERER [🔗](./http-uppercaserer.js)
> HTTP POST request
### # through2-map package
- `map` function : create a transform stream data
- takes a chunk of data and returns a chunk of data
```js
/* a chunk character reverser */
const map = require('through2-map');
inStream
.pipe(
map(function (chunk) {
return chunk.toString().split('').reverse().join('');
})
)
.pipe(outStream);
```
## 13. HTTP JSON API SERVER [🔗](./http-json-api-server.js)
> HTTP server that serves JSON data
### # url module
> "route" requests for endpoints
- Node core library
- `new URL(url)` : parse content of `url` and provide an object with helpful properties
```bash
$ node -pe "new URL('/test?q=1', 'http://example.com')"
```
### # JSON data
- `JSON.stringify()` : converts a JavaScript object or value to a JSON string
- set Content-Type : `res.writeHead(200, { 'Content-Type': 'application/json' })`
### # Date
- `new Date().toISOString()` : print dates in ISO format
- `new Date().getTime()` : get UNIX epoch time in milliseconds