枚举对象的属性

Question

给定以下类，我如何枚举它的属性，即获得像 [station1, station2, station3 ...] 这样的输出？

我只能看到如何枚举属性的值，即[null, null, null]。

class stationGuide {
    station1: any;
    station2: any;
    station3: any;

    constructor(){
        this.station1 = null;
        this.station2 = null;
        this.station3 = null;
     }
}

Answer 1

您有两个选择，使用Object.keys()，然后使用forEach，或者使用for/in：

class stationGuide {
    station1: any;
    station2: any;
    station3: any;

    constructor(){
        this.station1 = null;
        this.station2 = null;
        this.station3 = null;
     }
}

let a = new stationGuide();
Object.keys(a).forEach(key => console.log(key));

for (let key in a) {
    console.log(key);
}

(code in playground)

Answer 2

使用Reflect 对象，您可以以编程方式访问和修改任何对象。这种方法也不会抛出“元素隐式具有'any'类型，因为'string'类型的表达式不能用于索引类型'{}'”错误。

class Cat {
  name: string
  age: number

  constructor(name: string, age: number){
    this.name = name
    this.age = age
   }
}

function printObject(obj: any):void{
  const keys = Object.keys(obj)
  const values = keys.map(key => `${key}: ${Reflect.get(obj,key)}`)
  console.log(values)
}

const cat = new Cat("Fluffy", 5)
const dog = {
  name: "Charlie",
  age: 12,
  weight: 20
}

printObject(cat)
printObject(dog)

(code in playground)