利用ES6的proxy设置一个简单的验证器

const person = new Proxy(
    {
        name: 'Tom',
        age: 13
    },
    {
        set: (item, key, value) => {
            if(key === 'age') {
                if(value > 18) {
                    throw new RangeError('age is too big')
                } else {
                    item[key] = value
                }
            }
        }
    }
)
console.log(person.age = 12)
console.log(person.age = 19)