Learn about TypeScript data types in one article

let age: number = 10 // Number
let firstName: string = '凉宸' // String
let lastName: string = '凉宸' // String
let isMary: boolean = true // boolean
let unde: undefined = undefined // undefined
let nu: null = null // null

let isAny:any='any type any'
isAny=520
isAny=true
isAny=null

let userName: any = '凉宸';
// You can access any property console.log(userName.name);
console.log(userName.name.firstName);
// You can call any method userName.setName('David');
userName.setName('David').sayHello();
userName.name.setFirstName('David');

let ages: number[] = [5, 20, 13, 14]
let names: string[] = ['Liang Chen', 'Luffy', 'Ming Shiyin', 'Li Yangyong']

let arguments = [555,555,55]

function lei(){
  let arr:number=arguments
}

let arr:[number,string,boolean]=[520,'凉宸',true] 

let arr:[number,string,boolean]=[520,'凉宸',true]
arr.push('b') // OK arr.push(4) // OK arr.push(true) // OK console.log(arr)

let arr:[number,string]=[520,'凉宸']
arr.push('b') // OK arr.push(4) // OK arr.push(true) // No console.log(arr)

interface Point
  userName:string|number
  password:number
} // At this time, executing tsc will not parse the corresponding js code, because this type is unique to ts and only indicates constraints

interface Point
  userName:string|number
  password:number
}

let value:Point={
  userName:'[email protected]',
  password:123456
}

let val:Point={
  userName:55555,
  password:123456
} // At this time, both are met, and tsc is executed


// Only the following code appears, without any constraints js
var value = {
    userName: '[email protected]',
    password: 123456
};
var val = {
    userName: 55555,
    password: 123456
};

interface Point
  userName:string|number
  password:number,
  email?:string
}

let value:Point={
  userName:'[email protected]',
  password:123456
}

let val:Point={
  userName:55555,
  password:123456
}

interface Point
  userName:string|number
  password:number,
  email?:string,
  readonly address:string
}

let value:Point={
  userName:'[email protected]',
  password:123456,
  address:'Baoding'
}

let val:Point={
  userName:55555,
  password:123456,
  address:'Beijing'
}
value.password=65975222
value.address = 'kkk'

const value=():number=>{
  return 1
}

const val=():string=>{
  return 1
}

let value=5555

value='string'

let value:string|number
value = '凉辰'
value=520
value=true

function get(data:string|number):number{
  const str = data as string
  if(str.length){
    return str.length
  }else {
    const num = data as number
    return num.toString().length
  }
}

console.log(get('凉宸'));
console.log(get(520));

function get(data:string|number):number{
  if(typeof data==='string'){
    return data.length
  }else {
    return data.toString().length
  }
}

console.log(get('凉宸'));
console.log(get(520));

class Person {
  public name:string
  protected age:number
  private address:string
  constructor(name:string,age:number,address:string){
    this.name=name
    this.age=age
    this.address=address
  }
  speak(){
    console.log(`Person:${this.name}---${this.age}---${this.address}`)
  }
}
const Children = new Person('凉宸',20,'宝定')
Children.speak()
//Can output normally 

class Person {
  public name:string
  protected age:number
  private address:string
  constructor(name:string,age:number,address:string){
    this.name=name
    this.age=age
    this.address=address
  }
  speak(){
    console.log(`Person:${this.name}---${this.age}---${this.address}`)
  }
}

class child extends Person {
  say(){
    console.log(`child:${this.name}---${this.age}`)
  }
}
// const Children = new Person('凉宸',20,'宝定')
// Children.speak()
const children = new child('凉宸',20,'宝定')
children.say()

class Person {
  public name:string
  protected age:number
  private address:string
  constructor(name:string,age:number,address:string){
    this.name=name
    this.age=age
    this.address=address
  }
  speak(){
    console.log(`Person:${this.name}---${this.age}---${this.address}`)
  }
}

class child extends Person {
  say(){
    console.log(`child:${this.name}---${this.age}`)
  }
}
// const Children = new Person('凉宸',20,'宝定')
// Children.speak()
const children = new child('凉宸',20,'宝定')
children.say()

class Person {
  public name:string
  protected age:number
  private address:string
  constructor(name:string,age:number,address:string){
    this.name=name
    this.age=age
    this.address=address
  }
  speak(){
    console.log(`Person:${this.name}---${this.age}---${this.address}`)
  }
}

class child extends Person {
  say(){
    console.log(`child:${this.name}---${this.age}`)
  }
}
const Children = new Person('凉宸',20,'宝定')
Children.speak()
console.log(Children.address);
console.log(Children.age);

// const children = new child('凉宸', 20, '宝定')
// children.say()

enum Week {
  SUNDAY = 'Sunday',
  MONDAY = 'Monday',
  TUESDAY = 'Tuesday',
  WEDNESDAY = 'Wednesday',
  THURSDAY = 'Thursday',
  FRIDAY = 'Friday',
  SATURDAY = 'Saturday'
}
function getProgramme(date: Week): string {
  if (date === Week.SUNDAY) {
  return 'Sunday leisure and entertainment'
  } else if (date === Week.MONDAY) {
  return 'Blog post on Monday'
  } else if (date === Week.TUESDAY) {
  return 'Tuesday sprint'
  }
  else if (date === Week.WEDNESDAY) {
  return 'Continue to fight on Wednesday'
  }
  else if (date === Week.THURSDAY) {
  return 'New article on Thursday'
  }
  else if (date === Week.FRIDAY) {
  return 'Ready to rest on Friday'
  }
  else {
  return 'Sleep on Saturday'
  }
  }
  console.log(getProgramme(Week.THURSDAY));