[comment]: # "markdown: { smartypants: true }" ## On Node.js ## Part 2: On Node.js

<img title="node.js: official logo" src="https://nodejs.org/static/images/logos/nodejs-new-pantone-black.svg" width="60%" /> https://nodejs.org/en/about/resources/

# Prelude

If you don't have a _really_ good reason to use Rust 🦀

... you should almost certainly be using Go. 🐹

### Why?

<img title="node.js: an absolute dumpster fire" src="https://i.imgur.com/OlolkHa.png" width=70% />

- Microsoft - C# (TS) [WikiPedia: TypeScript](https://en.wikipedia.org/wiki/TypeScript) - Yahuda Katz - Ruby (Ember) https://yehudakatz.com - CoffeeScript - Ruby - Elm - Erlang (Elixer) - JSX - OCaml (Reason) [React to the Future](https://www.youtube.com/watch?v=5fG_lyNuEAw) - Straight-up Ignorance - [TC-39 Proposal: RegExp.escape (comment)](https://github.com/tc39/proposal-regex-escaping/issues/37#issuecomment-1056902176)


> The Problem with React is JavaScript <br>- Creator of > React <small>(paraphrased)</small>

React to the Future (2019) <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/5fG_lyNuEAw?start=114" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> <small><a href="https://www.youtube.com/watch?v=5fG_lyNuEAw?t=114">https://youtube.com/watch?v=5fG_lyNuEAw?t=114</a></small> <small> <ul> <li>1:54 - 2:14</li> </ul> </small>

If you stand for nothing, You will fall for anything. 💔

<img src="https://i.imgur.com/OwZqa2V.png" />

<img src="https://i.imgur.com/Ia6lnEj.png" />


<iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/Uo3cL4nrGOk?start=323" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> https://youtu.be/Uo3cL4nrGOk?t=323

I _do_ love JavaScript... but it's a minefield 💣

Y U No TypeScript!?!?

> When you mix two complex things together, you typically > get the multiplication of their demerits, not the sum of > their benefits (again, [WikiPedia: TypeScript](https://en.wikipedia.org/wiki/TypeScript))

# Node.js Gems

### 0. Install

Consistent, Conflict-free Install <https://webinstall.dev/node>

- ~~brew~~ - ~~nvm~~ - ~~pkg~~ - ~~exe~~ - tar + webi

### 1. Less is More

JavaScript vs "The Good Parts" <img width="600px" src="https://i.imgur.com/bxmJwGr.jpg" />

vs ECMAScript <img width="600px" src="https://i.imgur.com/bxmJwGr.jpg" /> <img height="400px" src="https://i.imgur.com/3QYPIIb.jpg" />

### 2. Classless

[beyondcodebootcamp.github.io/presos/classless-javascript](https://beyondcodebootcamp.github.io/presos/classless-javascript/)

Classless JavaScript (2021) <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/-wz2Ued0Zkc?start=337" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> <small><a href="https://www.youtube.com/watch?v=-wz2Ued0Zkc">https://youtube.com/watch?v=-wz2Ued0Zkc</a></small> <small> <ul> <li>5:37 - 6:22</li> </ul> </small>

- "flat is better than nested" - [Zen of Python](https://github.com/ewjoachim/zen-of-python) - serializable as JSON - avoid shallow abstractions

Single, Package-level Export ```js var Person = module.exports; ```

Simple, this-less "constructor" ```js Person.create = function (p) { var person = { name: p.name || "Another Jane Doe", age: p.age || 0, }; // ... return person; }; ```

Package-level public methods ```js Person.save = async function (p) { return await request({ url: `/api/person/${p.id}`, json: p, }); }; ```

Private data via Closures ```js Person.create = function (p) { var person = { /* ... */ }; person.creditCard = function () { return "****-****-****-" + p.creditCard.slice(-4); }; // ... return person; }; ```

_"Composition over Inheritance"_ ```js function createApiRequester(baseUrl, key, secret) { return async function (url, data) { return await request({ url: `${baseUrl}/${url}`, auth: { user: key, pass: secret }, json: data, }); }; } ```

```js Person.api = createApiRequester( "https://example.co", "my-user", "my-token" ); await Person.api("/api/person/1"); await person.api("/api/person/1", { name: "AJ" }); ```

### 3. Array Methods

Don't

> Better to be absent of semantic meaning than to portray > the **wrong** semantic meaning.

<img src="https://i.imgur.com/wBs4K8d.jpg" />

> `reduce` is for **lossy** aggregation

```js [5, 4, 3, 2, 1].reduce(function (total, val) { return total + val; }); ``` <small>the sum of the whole cannot be represented as its component parts</small>

~~When in doubt~~ Always, `forEach()`.

```js var friendsMap = {}; friends.forEach(function (f) { friendsMap[f.id] = f; }); ```

### 4. ❌ Generics

Avoid useless abstractions <small>(particularly `lodash`, syntax sugar)</small>

_"a little copying is better than a little dependency"_ ```js // ❌ leftpad(str, n, c); ``` ```js // ✅ String#padStart(n, c) ```

_"shallow abstractions do nothing in the fight against complexity"_ ```js // ❌ _.map(arry, fn); ``` ```js // ✅ arr.map(fn); ```

Explicit over implicit (low-context over high-context) ```js // ❌ [...arr]; ``` ```js // ✅ arr.slice(0); ```

```js // ❌ const foo = (x) => !x; ``` ```js // ✅ function foo(x) { return !x; } ```

Ternaries are the devil's playground ```js // ❌ let x = cond ? "special" : "default"; ``` ```js // ✅ "make the zero value useful" let x = "default"; if (cond) { x = "special"; } ```

No nesting templates ```js // ❌ (contrived, but you get the point) let greeting = `Hello, ${`${p.getTitle()} ${p.getName()}`}!`; ``` ```js // ✅ let title = p.getTitle(); let name = p.getName(); let greeting = `Hello, ${title} ${name}!`; ```

Stick to the built-in tooling <br><small>(unless you have a <em>very</em> good reason not to!)</small> - pnpm - yarn - ... 🤮

**5. AJScript**

_"The Missing Pieces"_, on Speed Dial [github.com/coolaj86/AJScript/issues?q=label=std](https://github.com/coolaj86/AJScript/issues?q=label%3Astd)

- `Date._toLocalISOString()` - `Promise._sleep()` - `Promise._forEach()` - `Promise._map()` - `Math._randomInt()` - `RegExp._escape()`

(for top-level packages only: don't include in libraries)

### 6. Nothingness

- null - "not defined" - `undefined` - `delete` - `false` - `""` - `0`

```js // 🤷‍♂️ person.spouse = null; // 'object' === typeof person.spouse ``` ```js // 🤷‍♂️ person.spouse = undefined; ``` ```js // 🤷‍♂️ delete person.spouse; ```

```js if ("spouse" in person) { // ... } ``` ```js if (person.spouse) { // ... } ``` ```js JSON.stringify(person); ```

```js if ("spouse" in person) { // ... } ``` ```js Object.keys(person); ``` ```js { ...person } ```

```js person.felon = person.felon ?? true; ``` ```js person.felon = person.felon || true; ```

### 7. const, let, var

The TRUTH about const, let, & var (2022) <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/snrAnYQ9NXE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> <small><a href="https://www.youtube.com/watch?v=snrAnYQ9NXE">https://youtube.com/watch?v=snrAnYQ9NXE</a></small>

const: No such thing. ```js const person = { name: "AJ" }; person.name = "Mysterio"; ```

ALL CAPS, or bust ```js const PI = 3.141_592_653_589_793; ```

let go... ```js { let x = 11; { let x = 37; { let x = 42; } } { let x = 42; } } ```

let down... (temporal dead zone) ```js switch (x) { case 11: { let y = 11; } break; default: { let y = 11; } } ```

let me die... ```js foo: { bar: "baz"; } ```

`var`: Just Works™

### 8. await / catch

Don't trade one pyramid of doom for another... ```js // ❌ try { asyncable(); } catch (e) { // swallow error ?? } ``` ```js // ✅ await asyncable().catch(function (err) { // Correct or Classify, but do not Catch to silence... // (let errors bubble until they burst) }); ```

### 9. async router (proper error handling in express)

https://github.com/therootcompany/async-router

Async, Await, and Promises in Express for Node.js <iframe width="560" height="315" src="https://www.youtube-nocookie.com/embed/XFn0SJmGYs4" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe> <small><a href="https://www.youtube.com/watch?v=XFn0SJmGYs4">https://youtube.com/watch?v=XFn0SJmGYs4</a></small>

```js let server = express(); let app = new require("@root/async-router").Router(); app.get("/api/hello", async function (req, res) { // ... }); server.use(app); ```

Alternatively... ```js let server = express(); let app = express.Router(); app.get("/api/hello", function (req, res) { Promise.resolve() .then(async function (req, res) { // ... }) .catch(next); }); server.use(app); ```

Use the built-in error handler! ```js app.use("/", function (err, req, res, next) { if (isSafe(err)) { res.json(err); return; } console.error(err); res.statusCode = 500; res.json({ message: "internal error" }); }); ```

### 10. Buffers & Streams

Pipe, whenever possible. ```js input.pipe(output); ``` ```js let rs = Fs.createReadStream(fullpath); rs.name; // the file's name! rs.pipe(res); ```

Never use `data`! ```js rs.on("readable", function () { for (;;) { var chunk = rs.read(); if (!chunk) { break; } // ... } }); ```

## Porty Time! 🥳 🚽