The class method

class Dog {
  constructor(name: string) {
     this.name = name
  }
  name: string
  run(){}}let dog = new Dog('wangwang')
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1. Constructor parameters and member attributes are annotated with type annotations
2. If the constructor does not givenameAttribute assignment, which is required when writing codenameProperty to set an initial value, otherwise an error is reported
3. If you don’t want to set the initial value, you can change it tonameSet to an optional propertyname? : string

inheritance

class Husky extends Dog {
  constructor(name: string, color: string) {
    super(name)
    this.color = color
  }
    color: string
}
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The modifier

public

All members of a class are public by default, meaning they are visible to everyone and can be explicitly declared

class Dog {
  constructor(name: string) {
     this.name = name
  }
  public name: string
  run(){}}let dog = new Dog('wangwang')
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private

Private members can only be called by the class itself, not by instances and subclasses of the class

class Dog {
  constructor(name: string) {
     this.name = name
  }
  public name: string
  run() {}
  private pri(){}}let dog = new Dog('wangwang')
dog.pri() / / an error

class Husky extends Dog {
  constructor(name: string, color: string) {
    super(name)
    this.color = color
    this.pri() / / an error
  }
    color: string
}
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The constructor is private, so the class cannot be instantiated or inherited

class Dog {
  constructor(name: string) {
     this.name = name
  }
  public name: string
  run() {}
  private pri() {}
  protect pro(){}}Copy the code

protected

Protected members can only be accessed in classes and subclasses, not in instances. Protected members cannot be instantiated, but can be inherited, as if declaring a base class

readonly

Read-only property that must be initialized and cannot be changed

class Dog {
  constructor(name: string) {
     this.name = name
  }
  readonly leg: number = 4
}
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Constructor parameters can also be modified to make them instance properties

class Husky extends Dog {
  constructor(name: string.public color: string) {
    super(name)
    this.color = color
  }
}
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static

Static modifiers, which can only be called by class name, not by instance, can be inherited,

class Dog {
  constructor(name: string) {
     this.name = name
  }
  static food: string = 'bones'
}
let dog = new Dog('wangwang')

Dog.food // bones
Husky.food // bones
dog.food // undefined
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