Symbol的使用

属性私有化——数据保护

//可修改
function Person(name, gender){
  this.name = name;
  this.gender = gender;
}
var p1 = new Person('莫莫', '女');

私有属性

var Person = (function(){
  var _gender = '';
  function P(name, gender){
    this.name = name;
    _gender = gender;
  }
  P.prototype.getGender = function(){
    return _gender;
  }
  return P;
})()

var p1 = new Person('莫莫', '女');
//p1得不到gender
//p1.getGender() 才能得到 gender

使用Symbol

var Person = (function(){
  var _gender = Symbol('gender');
  function P(name, gender){
    this.name = name;
    this.[_gender] = gender;
  }
  return P;
})()

var p1 = new Person('莫莫', '女');
//打印p1看得见女，取不到，外部访问不了