typescript- learning to use ts-3

function

Function Arguments

• Parameter and return type

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

• Optional parameters

function add(x: number, y?: number): number {
    return x + 10
}

• The default parameters

function add(x: number, y: number = 20): number {
    return x + y
}

• The remaining parameters

function sum(...args: number[]): number {
    let ret: number = 0
    args.forEach((item: number): void => {
        ret += item
    })
    return ret
}

sum(1, 2, 3)

Arrow function

• A basic example

let add = (x: number, y: number): number => x + y

for-of loop

• for loop
• forEach
  • It does not support the break
• for in
  • As will an array of objects to traverse
• for of
  • Support break

Type inference (Type Inference)

Type compatibility

Module

concept

Communication module: Export

export default xxx

export const foo: string = 'bar';
export const bar: string = 'foo';

Communicating: Import

// 加载默认成员
import xxx from '模块标识'

// 按需加载模块成员
import {foo, bar} from '模块'

TypeScript summary

• What is TypeScript
• Variable declaration
  • where
  • let
  • const
• Basic data types
  • Boolean value boolean
  • digital number
  • String string
  • Array number[]orArray<number>
  • Originator [number, string]
  • Object object, you can understand
  • Any type any
  • Function returns an empty value void
  • null with undefined
• interface
  • interface
• Deconstruction assignment
  • An array of deconstruction
  • Object deconstruction
• Operators Expand
  • Expand Arrays
  • Expand the object
• class
  • The basic syntax
  • Constructor
  • inherit
  • Property modifiers
  • get and set properties
• function
  • parameter
  • Arrow function
• for-of loop
• Module
  • Export
  • Importing