怎样用JS模拟实现枚举

这篇文章主要介绍了怎样用JS模拟实现枚举,对枚举感兴趣的同学,可以实验一下

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)

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