如何检查两个日期是否在同一日历日

Question

How to check if two dates not on the same day. I came up with this solution but maybe there is a better way to do this:

 var actualDate = new Date();
 var isNotToday = dateToCheck.getDay() !== actualDate.getDay() || dateToCheck < actualDate - 24 * 60 * 60 * 1000;

Answer 1

Another option is using .toDateString() function to parse both dates into strings. The function formats output to: "Wed Jul 28 1993." Then you can compare both date strings.

actualDate.toDateString() === dateToCheck.toDateString()
// returns true if actualDate is same day as dateToCheck

Here's a Plunker:

http://plnkr.co/edit/J5Dyn78TdDUzX82T0ypA

And more from MDN:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toDateString

Answer 2

How about checking for the same day, month & year:

var isSameDay = (dateToCheck.getDate() == actualDate.getDate() 
        && dateToCheck.getMonth() == actualDate.getMonth()
        && dateToCheck.getFullYear() == actualDate.getFullYear())

Answer 3

It would be safest to check day, month and year:

var isNotToday = dateToCheck.getDate() != actualDate.getDate()
      || dateToCheck.getMonth() != actualDate.getMonth()
      || dateToCheck.getFullYear() != actualDate.getFullYear();

This will ensure you don't get oddities when it comes to DST and leap years which could interfere otherwise.

Answer 4

function getStartOfDay(aDate){
    //returns the very beginning of the same day
    return new Date(aDate.getTime() - aDate.getTime() % 86400000);
}

var aDate1 = getStartOfDay(new Date());
var aDate2 = getStartOfDay(new Date(1981, 7, 3));

var result = aDate1.getTime() === aDate2.getTime();

Answer 5

Don't create the date object with a time so they're both generated at midnight. Then just check the epoch time.

new Date('11/12/2012').getTime() === new Date('11/11/2012').getTime()
> false
new Date('11/12/2012').getTime() === new Date('11/12/2012').getTime()
> true
new Date('November 12, 2012').getTime() === new Date('11/12/2012').getTime()
> true
new Date('12 November, 2012').getTime() === new Date('11/12/2012').getTime()
> true

The dates just need to be parseable by the Date object (I'm on chrome 23.0.1271.17 (Official Build 159779) beta) and if you don't pass a time they'll generate at midnight.

If you're getting a time, just drop it on the floor and test against midnight.

Answer 6

 function isEqual(startDate, endDate) { return endDate.valueOf() == startDate.valueOf(); } var now =new Date(); var startDate = new Date(now.getFullYear(), now.getMonth(), now.getDate()); var endDate = new Date(2017, 0, 13) var result = isEqual(startDate , endDate); console.log(result); 

Answer 7

Use a startOf method for instances of Date :

dateA.startOf('day').getTime() === dateB.startOf('day').getTime()

Here's the method:

Date.prototype.startOf = function(unit) {
    var clone = new Date(this.getTime()), day;
    /* */if (unit === 'second') clone.setMilliseconds(0);
    else if (unit === 'minute') clone.setSeconds(0,0);
    else if (unit === 'hour'  ) clone.setMinutes(0,0,0);
    else {
        clone.setHours(0,0,0,0);
        if (unit === 'week') {
            day = clone.getDay();
            clone = day ? new Date(clone - 1000 * 60 * 60 * 24 * day) : clone;
        }
        else if (unit === 'month') clone.setDate(1);
        else if (unit === 'year' ) clone.setMonth(0,1);
    }
    return clone;
};