JavaScript之定义属性

方式1

使用Object.defineProperty定义单个属性

‘use strict‘;

var person = { };

// 定义数据属性
Object.defineProperty(person, ‘_age‘, {
    configurable: true,
    writable: true,
    enumerable: true,
    value: -1,
});

// 定义访问器属性
Object.defineProperty(person, ‘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;
        }
    }
});

// -1
console.log(person.age);

person.age = 0;
// -18
console.log(person.age);

person.age = 30;
// 30
console.log(person.age);

方式2

使用Object.defineProperties方法定义多个属性

‘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;
            }
        }
    }
});

// -1
console.log(person.age);

person.age = 0;
// -18
console.log(person.age);

person.age = 30;
// 30
console.log(person.age);