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System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

User cases (description of sequences of events that, taken together, lead to a system doing something useful)
- Who is going to use it?
- How are they going to use it?

	class PoseSwiper extends Component<Props> {
	state = {
	activeIndex: 0
	};
	config = {
	slidesPerView: 1,
	observer: true,
	on: {
	slideChange: function(applyNewIndex: (index: number) => void) {
	applyNewIndex(this.activeIndex);

	{
	// Place your snippets for typescript here. Each snippet is defined under a snippet name and has a prefix, body and
	// description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
	// $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders. Placeholders with the
	// same ids are connected.
	// Example:
	// "Print to console": {
	// "prefix": "log",
	// "body": [
	// "console.log('$1');",

	{
	// Place your snippets for typescriptreact here. Each snippet is defined under a snippet name and has a prefix, body and
	// description. The prefix is what is used to trigger the snippet and the body will be expanded and inserted. Possible variables are:
	// $1, $2 for tab stops, $0 for the final cursor position, and ${1:label}, ${2:another} for placeholders. Placeholders with the
	// same ids are connected.
	// Example:
	// "Print to console": {
	// "prefix": "log",
	// "body": [
	// "console.log('$1');",

	FROM node:14-alpine AS backend-builder
	RUN apk --no-cache add curl
	RUN apk --no-cache add bash
	RUN curl -sfL https://install.goreleaser.com/github.com/tj/node-prune.sh \| bash -s -- -b /usr/local/bin

	WORKDIR /app
	COPY package.json yarn.lock ./
	RUN yarn --frozen-lockfile

	COPY . .

	// NOTE: this adds a filename and line number to winston's output
	// Example output: 'info (routes/index.js:34) GET 200 /index'

	var winston = require('winston')
	var path = require('path')
	var PROJECT_ROOT = path.join(__dirname, '..')

	var logger = new winston.logger({ ... })

	// this allows winston to handle output from express' morgan middleware

	type QueryParam = "size" \| "color" \| "page"

	export const parseQueryParam = <T extends QueryParam>(queryParam: T) : T => {
	return queryParam
	}