检查 typescript 类是否有 setter/getter

我有一个打字稿类，它具有以下属性：

export class apiAccount  {
    private _balance : apiMoney;
    get balance():apiMoney {
        return this._balance;
    }
    set balance(value : apiMoney) {
        this._balance = value;
    }

    private _currency : string;
    get currency():string {
        return this._currency;
    }
    set currency(value : string) {
        this._currency = value;
    }
    ...

我需要创建此类的空白实例：

let newObj = new apiAccount();

例如，然后检查它是否具有“货币”的设置器。 我以为这正是getOwnPropertyDescriptor确实如此，但显然我错了：

Object.getOwnPropertyDescriptor(newObj, 'currency')
Object.getOwnPropertyDescriptor(newObj, '_currency')

These both return undefined. But chrome seems to do it! When I hover over the instance, it shows me the properties, and shows them as undefined. How can I get a list of those property names, or check if the property descriptor exists in the object?

“问题”在于Object.getOwnPropertyDescriptor- 顾名思义 - 只返回一个描述符对象自身的属性。即：仅直接分配给该对象的属性，not来自其原型链中的对象之一的那些。

在你的例子中，currency属性定义于apiAccount.prototype， 不开newObj。以下代码片段演示了这一点：

class apiAccount {
    private _currency : string;
    get currency():string {
        return this._currency;
    }
    set currency(value : string) {
        this._currency = value;
    }
}

let newObj = new apiAccount();
console.log(Object.getOwnPropertyDescriptor(newObj, 'currency')); // undefined
console.log(Object.getOwnPropertyDescriptor(apiAccount.prototype, 'currency')); // { get, set, ... }

如果您想在对象原型链中的任何位置查找属性描述符，则需要循环Object.getPrototypeOf:

function getPropertyDescriptor(obj: any, prop: string) : PropertyDescriptor {
    let desc;
    do {
        desc = Object.getOwnPropertyDescriptor(obj, prop);
    } while (!desc && (obj = Object.getPrototypeOf(obj)));
    return desc;
}

console.log(getPropertyDescriptor(newObj, 'currency')); // { get, set, ... }