怎样用JS模拟实现枚举

前言

在当前的JavaScript中，并没有枚举这个概念，在某些场景中使用枚举更能保证数据的正确性，减少数据校验过程，下面就介绍一下JavaScript如何模拟实现枚举效果。

枚举主要特点

• 枚举值不能重复

• 不能被修改

实现

let days;
(function (days) {
   days[days["Sunday"] = 0] = "Sunday";
   days[days["Monday"] = 1] = "Monday";
   days[days["Tuesday"] = 2] = "Tuesday";
   days[days["Wednesday"] = 3] = "Wednesday";
   days[days["Thursday"] = 4] = "Thursday";
   days[days["Friday"] = 5] = "Friday";
   days[days["Saturday"] = 6] = "Saturday";
})(days || (days = {}));

这个时候days对象基本实现了枚举效果，可以通过枚举值或索引去访问days对象，但枚举有个重要特别是不能被修改，这个时候days是可以随意修改的；可以通过Object.freeze函数让对象不改修改，重新导出一个不可以修改的对象，完整代码如下：

let days;
(function (days) {
   days[days["Monday"] = 1] = "Monday";
   days[days["Tuesday"] = 2] = "Tuesday";
   days[days["Wednesday"] = 3] = "Wednesday";
   days[days["Thursday"] = 4] = "Thursday";
   days[days["Friday"] = 5] = "Friday";
   days[days["Saturday"] = 6] = "Saturday";
   days[days["Sunday"] = 0] = "Sunday";
})(days || (days = {}));

//导出可枚举对象
export EnumWeek = Object.freeze(days)

来源：https://www.cnblogs.com/qianxiaox/p/13744683.html