/** 对象属性保护* 方式1* */{    function Person() {        var data ={            name:'lee',            age:18,            sex:'0'        }        this.get = function (key) {            return data.key        }        this.set = function (key,value) {            if (!key == sex){                data.key = value            }        }    }    var person = new  Person(); //sex属性受保护}/** 方式2* defineProperty* */{    var person = {        name:'lee',        age:18    }    Object.defineProperty(person,'sex',{ //定义一个sex属性，设置为只读属性        writable:false,        value:0    })}/** 方式3* 对象代理* */{    let person = {        name:'lee',        age:18,        sex:0    }    let p = new Proxy(person,{        get(target,key){            return target.key        },        set(target,key,value){            if (key !== 'sex'){                target.key = value            }        }    })    //p.sex = 1;}