Object.getOwnPropertyDescriptor()

语法

getOwnPropertyDescriptor(o: any, p: PropertyKey): PropertyDescriptor | undefined;

描述

返回指定对象上一个自有属性对应的属性描述符。自有属性指的是直接赋予该对象的属性,因此原型链上的属性会返回 undefined.

示例

const obj = {
firstName: "Yancey",
lastName: "Leo",
greeting() {
return `Hello, ${this.firstName}!`;
}
};
Object.defineProperties(obj, {
age: {
value: 18,
enumerable: true
},
lastName: {
get() {
return "Yancey";
}
}
});
Object.getOwnPropertyDescriptor(obj, "firstName");
// 输出: {value: 'Yancey', writable: true, enumerable: true, configurable: true}
Object.getOwnPropertyDescriptor(obj, "lastName");
// 输出:{get: [Function: get], set: undefined, enumerable: true, configurable: true}
Object.getOwnPropertyDescriptor(obj, "age");
// 输出:{value: 18, writable: false, enumerable: true, configurable: false}

而对于原型链上的属性,该方法直接返回 undefined

function Dog(name, color) {
this.name = name;
this.color = color;
}
Dog.prototype.bark = function() {
return "汪汪~";
};
const husky = new Dog("旺财", "pink");
Object.getOwnPropertyDescriptor(Dog, "bark"); // false
Object.getOwnPropertyDescriptor(Dog, "name");
// 输出:{value: 'Dog', writable: false, enumerable: false, configurable: true}
Object.getOwnPropertyDescriptor(husky, "name");
// 输出:{value: '旺财', writable: true, enumerable: true, configurable: true}
Last updated on by YanceyOfficial