JavaScript日期对象比较 [英] JavaScript Date Object Comparison

问题描述

在比较Javascript中的日期对象时，我发现即使比较相同的日期也不会返回true。

When comparing date objects in Javascript I found that even comparing the same date does not return true.

 var startDate1 = new Date("02/10/2012");
 var startDate2 = new Date("01/10/2012");
 var startDate3 = new Date("01/10/2012");
 alert(startDate1>startDate2); // true
 alert(startDate2==startDate3); //false

我如何比较这些日期的相等性？我有兴趣利用JS的原生 Date 对象，而不是任何第三方库，因为它不适合使用第三方JS来比较日期。

How could I compare the equality of these dates? I am interested in utilizing the native Date object of JS and not any third party libraries since its not appropriate to use a third party JS just to compare the dates.

推荐答案

这是因为在第二种情况下，比较实际日期对象，并且两个对象永远不会彼此相等。强制他们编号：

That is because in the second case, the actual date objects are compared, and two objects are never equal to each other. Coerce them to number:

 alert( +startDate2 == +startDate3 ); // true

如果您想要更明确地转换为数字，请使用：

If you want a more explicity conversion to number, use either:

 alert( startDate2.getTime() == startDate3.getTime() ); // true

或

 alert( Number(startDate2) == Number(startDate3) ); // true

哦，对规范的引用：§11.9.3抽象等式比较算法，基本上说在比较对象时， obj1 == obj2 仅当它们引用同一个对象时才为真，否则结果为false。

Oh, a reference to the spec: §11.9.3 The Abstract Equality Comparison Algorithm which basically says when comparing objects, obj1 == obj2 is true only if they refer to the same object, otherwise the result is false.

这篇关于JavaScript日期对象比较的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！