Ref Link: https://paper.dropbox.com/doc/Intro-to-TypeScript-DLvvIv9jdt2XdnawLK9AX

Basic types and variable declarations

const study: string = ‘study’;

Primitives and Non-primitives

Primitives

  • boolean
  • number
  • string
  • null
  • undefined (sometimes annotated as void)

Non-primitives

I like to think of composite types as data structures that can “contain” other types.

  • Array - e.g. [3, 1, 4]
  • Object, aka “plain object” - e.g. { key: “value” }
  • An instance of a class - e.g. new Date()
  • Function - e.g. (a, b) => a + b

Typing function arguments and return types

you can add types for function parameter and return type

function add(x: number, y: number): number {
    return x + y;
}