JavaScript之读取属性特征

‘use strict‘;

var person = { };

Object.defineProperties(person, {
    _age: {
        configurable: true,
        writable: true,
        enumerable: true,
        value: -1,
    },
    age: {
        configurable: false,
        enumerable: false,
        get: function () {
            return this._age;
        },
        set: function (newValue) {
            if (newValue <= 0 || newValue > 100) {
                this._age = 18;
            } else {
                this._age = newValue;
            }
        }
    }
});

var descriptor1 = Object.getOwnPropertyDescriptor(person, ‘_age‘);
// true
console.log(descriptor1.configurable);
// true
console.log(descriptor1.writable);
// true
console.log(descriptor1.enumerable);
// -1
console.log(descriptor1.value);

var descriptor2 = Object.getOwnPropertyDescriptor(person, ‘age‘);
// false
console.log(descriptor2.configurable);
// false
console.log(descriptor2.enumerable);
// [Function]
console.log(descriptor2.get);
// [Function]
console.log(descriptor2.set);