Node for Novices

# Node for Novices

### Sean Duncan
### (MetaSean)

???

Notes for the _first_ slide!

---

# What is Node.js?

>"Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient. Node.js' package ecosystem, npm, is the largest ecosystem of open source libraries in the world."  
https://nodejs.org/en/

---

# No, really, what is Node.js?

A stand-alone runtime environment for JavaScript.

- _not_ for browsers 
- _for_ servers, hardware, your own laptop, etc 
- starts with the same JavaScript engine as Chrome (i.e. V8)
- includes additional libraries (e.g. file handling)
--

- has a great, open-source ecosystem of other modules

--
- for a novice ☝️ are a good set of features to initially focus on, _but yes_, Node.js also has other awesome features!
--

---

# How to play with Node.js tonight

_Note_:  I'll be demoing in CodeAnywhere tonight,  
    **_but it's better to work locally if you can!_**

**If you already have node and an IDE or texteditor  installed:**
  1. Create a new directory for tonight's code along (e.g. 'purple-people-eater')
  
**If you do *_not_* already have node installed:**
  1. Go sign up for an account at [codeanywhere.com](https://codeanywhere.com)
  2. Create a new project (e.g. 'purple-people-eater')
  3. Add a new Connection Wizard, specifically the Node.js stack on Ubuntu

---

# Quick CodeAnywhere Tour

- View 👉 Layout 👉 Columns:2
- View 👉 File Explorer (`⌥-X`; `option-X`)
- View 👉 MiniMap (uncheck)
- Terminal tab: right-click project name 👉 SSH Terminal
- User 👉 Dashboard 👉 Projects
- Distraction-free mode: `⌘-ctl-⇧-F`
- New file: `ctrl-N`

---

# Initialize a local repository

```bash
 npm init
```
_or_
```bash
 /* use this version tonight */
 `npm init --yes` 
```
  
- [Relevant field descriptions](https://docs.npmjs.com/files/package.json)
]]

---

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.columns[.col-left[
  ## `npm init`
  ## `package.json`
]
.col-right[

# `package.json`

This file contains relevant metadata about your project, including other projects —known as 'modules'— that your project depends upon.

]]

---

layout: false
.columns[.col-left[
  ## `npm init`
  ## `package.json`
  ## `node_modules`
]
.col-right[

# `node_modules`

The `node_modules` directory contains any other node modules that you indicated that your project depends upon.
]]

---

layout: false
.columns[
.col-left[
  ## `npm init`
  ## `package.json`
  ## `node_modules`
  ## `yarn`
]
.col-right[

# `yarn`

- `yarn` is itself another node package…
- which reimplements some `npm` functionality.

You can install Yarn via:
```bash
npm install yarn --global
```
]
]

---

# Local Installations

```bash
npm install learnyounode
```

- `npm install` installs one or more node modules
- in this case, it installs the `learnyounode` module
- if no module name is provided, but there is another file (we'll look at that file in a moment) which  includes dependencies, then it will install those modules

]
]

---

layout: false
.columns[
.col-left[
  ## local install
  ## local bin
]
.col-right[

# Local `bin`

```bash
node node_modules/learnyounode/bin/learnyounode
```

- `node` runs the file listed immediately following it
- in this case the file includes a path from the current working directory and the filename, where: 
  - `node_modules/learnyounode/bin/` is the path
  - `learnyounode` is the filename  
    (which does not have the usual `.js` extension)

]
]
---

layout: false
.columns[
.col-left[
  ## local install
  ## local bin
  ## REPL
]
.col-right[

# REPL

```bash
node 
```

- running it without any paramaters switches your terminal / command line to a Node REPL (Read-eval-print loop)
  - **_If you want to, follow-along with this part._**
  - `node`
  - you'll notice the terminal prompt changes
  - `1+1` >>> `2`
  - `^-C` (ctrl-C) - _twice_ to exit the REPL mode

]
]

---

layout: false
.columns[
.col-left[
  ## local install
  ## local bin
  ## REPL
  ## scripts
]

# Scripts

```javascript
/* package.json */
"scripts": {
  "teachMeNode": "node node_modules/learnyounode/bin/learnyounode"
},
```

Run the package's script with either:  
```bash
npm run teachMeNode
```
_OR_

```bash
yarn run teachMeNode
```
_OR_

```bash
yarn teachMeNode
```

]
]
]
]
]
]

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.col-left[
  ## local install
  ## local bin
  ## REPL
  ## scripts
]
.col-right[

# Scripts

### Custom scripts names for that npm project  
- require `run`, e.g. `npm run teachMeNode` 
- if there are no other command line or terminal commands with the same name, `yarn` does not require the `run` parameter

### Standard scripts associated with any npm project  
- e.g. `test`, `start`, `stop` don't require `run`, e.g. `npm test`  
- https://docs.npmjs.com/misc/scripts for the full list

]
]

---

layout: false
.columns[
.col-left[
  ## local install
  ## local bin
  ## REPL
  ## scripts
  ## global install
]
.col-right[

# Global Installations

Go ahead and run this command now:
```bash
 `npm install learnyounode --global`
```

- available from anywhere on your computer 
- global packages _can_ set-up their own global command line/terminal scripts
  - for example, you now have a `learnyounode` command available

]
]

---

# Node School

**"learnyounode"** is just one of many self-based [workshoppers](https://nodeschool.io/#workshopper-list) available at [nodeschool.io](https://nodeschool.io/#workshopper-list) to help you learn essential Node.js-related skills.
  
--

----
  
**_Once you have the `learnyounode` workshopper installed, start working through it by running:_**
```bash
 `learnyounode`
```

---

# 01-hello-world.js

```javascript
console.log("HELLO WORLD")
```

- [`console.log`](https://nodejs.org/dist/latest-v8.x/docs/api/console.html#console_console_log_data_args)

---

# 02-baby-steps.js

```javascript
const [cmd, file, `...numberArray`] = `process.argv`
const sum = nums `=>` nums`.reduce`( 
    (reduction, current) => 
        reduction + parseInt(current),
    0
)
`console.info`( sum(numberArray) )
```

- `...numberArray`, i.e. [destructuring assignment]( https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Destructuring_assignment)
-  [`process.argv`](https://nodejs.org/dist/latest-v8.x/docs/api/process.html#process_process_argv)
- `=>`, i.e. [arrow function expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions)
- [Array's `reduce()` function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce)
- [`console.info`](https://nodejs.org/api/console.html#console_console_info_data_args)

---

# 03-my-first-io.js

```javascript
const fs = require('fs')

const fileName = process.argv[2]
const fileBuffer = fs.readFileSync(fileName)
const fileContents = fileBuffer.toString()
const linesInFile = fileContents.split('\n')
const newLineCount = linesInFile.length - 1

console.log(newLineCount)
```

- `fs`, i.e. [File System]( https://nodejs.org/dist/latest-v8.x/docs/api/fs.html)
- [`Buffer`](https://nodejs.org/dist/latest-v8.x/docs/api/buffer.html)

---

# 04-my-first-async-io.js

```javascript
const fs = require('fs')

const fileName = process.argv[2]
fs.readFile(fileName, countLines)

function countLines (err, data) {
  if (err) { throw err }
  const newLineCount = data.toString()
                           .split('\n')
                           .length - 1

console.log(newLineCount)
}
```

- [`throw`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/throw)
- [`fs.readFile`]( https://nodejs.org/dist/latest-v8.x/docs/api/fs.html#fs_fs_readfile_path_options_callback)
- [Art of Node:  Callbacks](https://github.com/maxogden/art-of-node#callbacks)
]
]

---

# 07-http-client.js

```javascript
const http = require('http')

const handleResponse = response =>
  response.setEncoding('utf8')
          .on('data', console.log)
          .on('error', console.error)

http.get(process.argv[2], handleResponse)
    .on('error', console.error)
}
```
]

---

**Stay Curious**  
**and**  
**Keep Coding!**

]