Nest.js学习笔记（三）

// 普通类装饰器(不可传参)
const doc: ClassDecorator = (target: any) => {
    console.log(target)
}

@doc
class Xiaoman {
    constructor() {}
}

// 类工厂装饰器(可自由传参)
const docs = (str: string): ClassDecorator => {
    return (target: any): void => {
        console.log(str)
    }
}

@docs('这是一段字符串')
class XiaomanFactory {
    constructor() {}
}

// 属性装饰器(返回构造函数和属性名)
const props: PropertyDecorator = (target: any, key: string | symbol) => {
    console.log(target, key)
}

class XiaomanProperty {
    @props
    public name: string
    constructor() {
        this.name = '小满'
    }
}

// 方法装饰器(返回构造函数、方法名和方法定义)
const method:MethodDecorator = (target: any, propertyKey: string | symbol,descriptor:any) => {
    console.log(target,propertyKey,descriptor);
}

class XiaomanMethod {
    constructor(){}
    @method
    getName(){}
}

// 参数装饰器(返回构造函数、参数名和参数所在位置(从前往后递减))
const param:ParameterDecorator = (target:any,propertyKey: string | symbol,parameterIndex: number) => {
    console.log(target,propertyKey,parameterIndex)
}

class XiaomanParams {
    constructor(){}
    myMethod(@param data:any,@param key:any){}
}

// 装饰器底层实现
class CustomXiaoman {
    constructor(){}
}
const custom = (target:any) => {
    console.log(target)
}
custom(CustomXiaoman)