TypeScript Notes

yarn init
yarn add -D typescript
yarn run tsc --init

yarn add -D ts-node-dev
"scripts": {
 "dev": "ts-node-dev --respawn --transpile-only index.ts"
},
yarn run dev

yarn add eslint --dev
yarn create @eslint/config
yarn add -D eslint-config-standard
yarn add -D @typescript-eslint/eslint-plugin
yarn add -D @typescript-eslint/parser
yarn add -D eslint-plugin-import
yarn add -D eslint-plugin-node
yarn add -D eslint-plugin-promise

"root": true

let cats: string[] = ['Bob', 'Willy', 'Mini']

// add to end
cats.push('cat')

// remove from the end
let cat: string = cats.pop()

// remove from beginning
let cat: string = cats.shift()

//add to beginning
cats.unshift('cat')

// loop
for (let cat of cats) {
  console.log(cat)
}

// clone
;[...cats]
Array.from(cats)

let h: { [index: string]: number } = { a: 1, b: 2 }

// value in hash
'a' in h

// number of keys
Object.keys(h).length

// loop
for (let key in h) {
  console.log(key)
  console.log(h[key])
}

let s: Set<string> = new Set<string>()

s.add('s')
console.log(s.has('s'))
s.delete('s')

Infinity

boolean