Object.freeze(): 冻结一个对象

• 冻结基础类型的属性

var person = {
    name: 'jack',
    skill: {}
}

Object.freeze(person)

person.name = 'aaa'

console.log(person)  // {name: "jack", skill: {}}

• 属性为对象的浅冻结

person.skill.name = 'eat'

console.log(person)  // {name: "jack", skill: {name: "eat"}}

Object.isFrozen(): 判断一个对象是否冻结

Object.isFrozen(person) // true