如何检查对象是否是日期？ [英] How to check whether an object is a date?

问题描述

我在网页上有一个烦人的错误：date.GetMonth（）不是一个功能。所以我想我做错了，因为某个地方，对象日期不是Date类型的对象。 我如何检查Javascript中的数据类型？我尝试添加一个 if（date）但不起作用。

I have an annoying bug in on a webpage: "date.GetMonth() is not a function". So I suppose that I am doing something wrong since somewhere and the object date is not an object of type Date. How can I check for a datatype in Javascript? I tried to add a if(date) but it doesn't work.

function getFormatedDate(date) {
    if (date) {
       var month = date.GetMonth();
    }
}

所以如果我想编写防御性代码，日期（不是一个）要格式化，我该怎么做？

So if I want to write defensive code and prevent the date (which is not one) to be formatted, how do I do that?

谢谢！

更新：我不想检查日期的格式，但我想确保传递给方法getFormatedDate的参数的类型为Date。

UPDATE: I don't want to check the format of the date, but I want to be sure that the parameter passed to the method getFormatedDate is of type Date.

推荐答案

通过

typeof date.getMonth === 'function'

可以使用 instanceof operator，ie但是它也将返回真实的无效日期，例如 new Date（'random_string'）也是Date的实例

you can use the instanceof operator, i.e. But it will return true for invalid dates too, e.g. new Date('random_string') is also instance of Date

date instanceof Date

如果对象跨越框架边界，这将失败。

This will fail if objects are passed across frame boundaries.

解决方法是通过

Object.prototype.toString.call(date) === '[object Date]'

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