首先,簡單介紹ES6的class類
class Foo {
constructor(name,age){ // 實例前的構造函數,實例添加name/age屬性
this.name = name
this.age = age
}
getName () { // 原型添加getName()方法
return `My name is ${this.name} age : ${this.age}`
}
}
let foo = new Foo('小明',12) // Foo {name:'小名',age:12,__proto__:getName(){}}
ts定義類:
class Foo {
public name:string // 需要提前聲明值,默認爲public
public age:number
public constructor(_name:string,_age:number){
this.name = _name
this.age = _age
}
public getName ():string { // 原型方法,指定返回值爲string類型
return `My name is ${this.name} age : ${this.age}`
}
}
let foo = new Foo('小明',12) // Foo {name:'小名',age:12,__proto__:getName(){}}
這裏指定name和age的類型,附部分類型:
attr : sting // sting類型
attr : number // number類型
attr : boolean // boolean類型
attr : string[] // 數組的每一項必須是string類型
attr : number[] // 數組每一項必須是number類型
attr : Array< any>// 數組每一項可以爲任意類型
attr : [string,number] // 數組每一項必須是指定類型
attr ?: string // 非必傳
提前聲明值可以利用參數屬性
class Foo {
public constructor(public name:string,public age:number){}
public getName ():void {
console.log(this.name,this.age)
}
}
let foo = new Foo(‘小明’,12) // Foo {name:'小明',age:12,__proto__:getName(){}}
介紹public、private、protected、readonly、static 等標識
- public (默認爲public,也可以設置爲public)
class Foo {
pulbic name:string
public constructor (_name?:string) {
this.name = _name || ''
}
}
let foo = new Foo('小明') // Foo {name:'小名'}
- private (可以被繼承,但是無法在實例中訪問)
class Foo {
private name:string
constructor (_name:string) {
this.name = _name
}
}
let foo = new Foo('小明') // Foo {name:'小名'}
console.log(foo.name) //error: Property 'name' is private;
- protected (與private類似,但是當構造函數是protected時,無法實例化,只能被繼承)
class Foo {
protected name:string
protected constructor(_name:string){
this.name = _name
}
}
let foo = new Foo('小明') //error: Constructor of class 'Foo' is protected
- readonly (只讀屬性,無法被修改/克隆)
class Foo {
readonly name:string
public constructor(_name:string){
this.name = _name
}
}
let foo = new Foo('小明') // Foo {name:'小明'}
foo.name = '小紅' //error: Cannot assign to 'name' because it is a constant or a read-only property.
- static (靜態屬性,不能被實例訪問,在類裏面訪問時,需要加上類名)
class Foo {
static age:number = 12
public constructor(private name:string){}
pubilc getAge ():void {
console.log(Foo.age)
}
}
let foo = new Foo('小明') // Foo {name:'小明',__proto__:getAge(){}}
console.log(foo.getAge()) // 12
ts繼承:
class Foo {
public name:string
public age:number
public construcor (_name:string,_age:number) {
this.name = _name
this.age = _age
}
getName ():string {
return this.name
}
}
class Bar extends Foo {
private className:string
public constructor (_name:string,_age:number,_className:string) {
super(_name,_age)
this.calssName = _className
}
public getClassName ():void {
console.log(this.className)
}
}
let bar = new Bar('小明',12,'一年級') // Bar {name:'小明',age:12,className:'一年級'}
console.log(bar.getName()) // 小明
console.log(bar.getClassName()) // 一年級