使用JavaScript按预期方式比较两个日期

Question

这是我的javascript代码:

var prevDate = new Date('1/25/2011'); // the string contains a date which
                                      // comes from a server-side script
                                      // may/may not be the same as current date

var currDate = new Date();            // this variable contains current date
    currDate.setHours(0, 0, 0, 0);    // the time portion is zeroed-out

console.log(prevDate);                // Tue Jan 25 2011 00:00:00 GMT+0500 (West Asia Standard Time)
console.log(currDate);                // Tue Jan 25 2011 00:00:00 GMT+0500 (West Asia Standard Time)
console.log(prevDate == currDate);    // false -- why oh why

请注意,两个日期都相同,但比较使用==表明它们不相同.为什么？

Answer 1

我不认为你可以==用来比较JavaScript中的日期.这是因为它们是两个不同的对象,因此它们不是"对象相等的".JavaScript允许您使用比较字符串和数字==,但所有其他类型都作为对象进行比较.

那是:

var foo = "asdf";
var bar = "asdf";
console.log(foo == bar); //prints true

foo = new Date();
bar = new Date(foo);
console.log(foo == bar); //prints false

foo = bar;
console.log(foo == bar); //prints true

但是,您可以使用该getTime方法获取可比较的数值:

foo = new Date();
bar = new Date(foo);
console.log(foo.getTime() == bar.getTime()); //prints true