Comparing date part only without comparing time in JavaScript
What is wrong with the code below?
Maybe it would be simpler to just compare date and not time. I am not sure how to do this either, and I searched, but I couldn't find my exact problem.
BTW, when I display the two dates in an alert, they show as exactly the same.
My code:
window.addEvent('domready', function() {
var now = new Date();
var input = $('datum').getValue();
var dateArray = input.split('/');
var userMonth = parseInt(dateArray[1])-1;
var userDate = new Date();
userDate.setFullYear(dateArray[2], userMonth, dateArray[0], now.getHours(), now.getMinutes(), now.getS开发者_开发技巧econds(), now.getMilliseconds());
if (userDate > now)
{
alert(now + '\n' + userDate);
}
});
Is there a simpler way to compare dates and not including the time?
I'm still learning JavaScript, and the only way that I've found which works for me to compare two dates without the time is to use the setHours method of the Date object and set the hours, minutes, seconds and milliseconds to zero. Then compare the two dates.
For example,
date1 = new Date()
date2 = new Date(2011,8,20)
date2 will be set with hours, minutes, seconds and milliseconds to zero, but date1 will have them set to the time that date1 was created. To get rid of the hours, minutes, seconds and milliseconds on date1 do the following:
date1.setHours(0,0,0,0)
Now you can compare the two dates as DATES only without worrying about time elements.
BEWARE THE TIMEZONE
Using the date object to represent just-a-date straight away gets you into a huge excess precision problem. You need to manage time and timezone to keep them out, and they can sneak back in at any step. The accepted answer to this question falls into the trap.
A javascript date has no notion of timezone. It's a moment in time (ticks since the epoch) with handy (static) functions for translating to and from strings, using by default the "local" timezone of the device, or, if specified, UTC or another timezone. To represent just-a-date™ with a date object, you want your dates to represent UTC midnight at the start of the date in question. This is a common and necessary convention that lets you work with dates regardless of the season or timezone of their creation. So you need to be very vigilant to manage the notion of timezone, both when you create your midnight UTC Date object, and when you serialize it.
Lots of folks are confused by the default behaviour of the console. If you spray a date to the console, the output you see will include your timezone. This is just because the console calls toString() on your date, and toString() gives you a local represenation. The underlying date has no timezone! (So long as the time matches the timezone offset, you still have a midnight UTC date object)
Deserializing (or creating midnight UTC Date objects)
This is the rounding step, with the trick that there are two "right" answers. Most of the time, you will want your date to reflect the local timezone of the user. What's the date here where I am.. Users in NZ and US can click at the same time and usually get different dates. In that case, do this...
// create a date (utc midnight) reflecting the value of myDate and the environment's timezone offset.
new Date(Date.UTC(myDate.getFullYear(),myDate.getMonth(), myDate.getDate()));
Sometimes, international comparability trumps local accuracy. In that case, do this...
// the date in London of a moment in time. Device timezone is ignored.
new Date(Date.UTC(myDate.getUTCFullYear(), myDate.getUTCMonth(), myDate.getUTCDate()));
Deserialize a date
Often dates on the wire will be in the format YYYY-MM-DD. To deserialize them, do this...
var midnightUTCDate = new Date( dateString + 'T00:00:00Z');
Serializing
Having taken care to manage timezone when you create, you now need to be sure to keep timezone out when you convert back to a string representation. So you can safely use...
toISOString()getUTCxxx()getTime() //returns a number with no time or timezone..toLocaleDateString("fr",{timeZone:"UTC"}) // whatever locale you want, but ALWAYS UTC.
And totally avoid everything else, especially...
getYear(),getMonth(),getDate()
So to answer your question, 7 years too late...
<input type="date" onchange="isInPast(event)">
<script>
var isInPast = function(event){
var userEntered = new Date(event.target.valueAsNumber); // valueAsNumber has no time or timezone!
var now = new Date();
var today = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate() ));
if(userEntered.getTime() < today.getTime())
alert("date is past");
else if(userEntered.getTime() == today.getTime())
alert("date is today");
else
alert("date is future");
}
</script>
See it running...
Update 2022... free stuff with tests ...
The code below is now an npm package, Epoq. The code is on github. You're welcome :-)
Update 2019... free stuff...
Given the popularity of this answer, I've put it all in code. The following function returns a wrapped date object, and only exposes those functions that are safe to use with just-a-date™.
Call it with a Date object and it will resolve to JustADate reflecting the timezone of the user. Call it with a string: if the string is an ISO 8601 with timezone specified, we'll just round off the time part. If timezone is not specified, we'll convert it to a date reflecting the local timezone, just as for date objects.
function JustADate(initDate){
var utcMidnightDateObj = null
// if no date supplied, use Now.
if(!initDate)
initDate = new Date();
// if initDate specifies a timezone offset, or is already UTC, just keep the date part, reflecting the date _in that timezone_
if(typeof initDate === "string" && initDate.match(/(-\d\d|(\+|-)\d{2}:\d{2}|Z)$/gm)){
utcMidnightDateObj = new Date( initDate.substring(0,10) + 'T00:00:00Z');
} else {
// if init date is not already a date object, feed it to the date constructor.
if(!(initDate instanceof Date))
initDate = new Date(initDate);
// Vital Step! Strip time part. Create UTC midnight dateObj according to local timezone.
utcMidnightDateObj = new Date(Date.UTC(initDate.getFullYear(),initDate.getMonth(), initDate.getDate()));
}
return {
toISOString:()=>utcMidnightDateObj.toISOString(),
getUTCDate:()=>utcMidnightDateObj.getUTCDate(),
getUTCDay:()=>utcMidnightDateObj.getUTCDay(),
getUTCFullYear:()=>utcMidnightDateObj.getUTCFullYear(),
getUTCMonth:()=>utcMidnightDateObj.getUTCMonth(),
setUTCDate:(arg)=>utcMidnightDateObj.setUTCDate(arg),
setUTCFullYear:(arg)=>utcMidnightDateObj.setUTCFullYear(arg),
setUTCMonth:(arg)=>utcMidnightDateObj.setUTCMonth(arg),
addDays:(days)=>{
utcMidnightDateObj.setUTCDate(utcMidnightDateObj.getUTCDate + days)
},
toString:()=>utcMidnightDateObj.toString(),
toLocaleDateString:(locale,options)=>{
options = options || {};
options.timeZone = "UTC";
locale = locale || "en-EN";
return utcMidnightDateObj.toLocaleDateString(locale,options)
}
}
}
// if initDate already has a timezone, we'll just use the date part directly
console.log(JustADate('1963-11-22T12:30:00-06:00').toLocaleDateString())
// Test case from @prototype's comment
console.log("@prototype's issue fixed... " + JustADate('1963-11-22').toLocaleDateString())How about this?
Date.prototype.withoutTime = function () {
var d = new Date(this);
d.setHours(0, 0, 0, 0);
return d;
}
It allows you to compare the date part of the date like this without affecting the value of your variable:
var date1 = new Date(2014,1,1);
new Date().withoutTime() > date1.withoutTime(); // true
Using Moment.js
If you have the option of including a third-party library, it's definitely worth taking a look at Moment.js. It makes working with Date and DateTime much, much easier.
For example, seeing if one Date comes after another Date but excluding their times, you would do something like this:
var date1 = new Date(2016,9,20,12,0,0); // October 20, 2016 12:00:00
var date2 = new Date(2016,9,20,12,1,0); // October 20, 2016 12:01:00
// Comparison including time.
moment(date2).isAfter(date1); // => true
// Comparison excluding time.
moment(date2).isAfter(date1, 'day'); // => false
The second parameter you pass into isAfter is the precision to do the comparison and can be any of year, month, week, day, hour, minute or second.
Simply compare using .toDateString like below:
new Date().toDateString();
This will return you date part only and not time or timezone, like this:
"Fri Feb 03 2017"
Hence both date can be compared in this format likewise without time part of it.
Just use toDateString() on both dates. toDateString doesn't include the time, so for 2 times on the same date, the values will be equal, as demonstrated below.
var d1 = new Date(2019,01,01,1,20)
var d2 = new Date(2019,01,01,2,20)
console.log(d1==d2) // false
console.log(d1.toDateString() == d2.toDateString()) // true
Obviously some of the timezone concerns expressed elsewhere on this question are valid, but in many scenarios, those are not relevant.
If you are truly comparing date only with no time component, another solution that may feel wrong but works and avoids all Date() time and timezone headaches is to compare the ISO string date directly using string comparison:
> "2019-04-22" <= "2019-04-23"
true
> "2019-04-22" <= "2019-04-22"
true
> "2019-04-22" <= "2019-04-21"
false
> "2019-04-22" === "2019-04-22"
true
You can get the current date (UTC date, not neccesarily the user's local date) using:
> new Date().toISOString().split("T")[0]
"2019-04-22"
My argument in favor of it is programmer simplicity -- you're much less likely to botch this than trying to handle datetimes and offsets correctly, probably at the cost of speed (I haven't compared performance)
This might be a little cleaner version, also note that you should always use a radix when using parseInt.
window.addEvent('domready', function() {
// Create a Date object set to midnight on today's date
var today = new Date((new Date()).setHours(0, 0, 0, 0)),
input = $('datum').getValue(),
dateArray = input.split('/'),
// Always specify a radix with parseInt(), setting the radix to 10 ensures that
// the number is interpreted as a decimal. It is particularly important with
// dates, if the user had entered '09' for the month and you don't use a
// radix '09' is interpreted as an octal number and parseInt would return 0, not 9!
userMonth = parseInt(dateArray[1], 10) - 1,
// Create a Date object set to midnight on the day the user specified
userDate = new Date(dateArray[2], userMonth, dateArray[0], 0, 0, 0, 0);
// Convert date objects to milliseconds and compare
if(userDate.getTime() > today.getTime())
{
alert(today+'\n'+userDate);
}
});
Checkout the MDC parseInt page for more information about the radix.
JSLint is a great tool for catching things like a missing radix and many other things that can cause obscure and hard to debug errors. It forces you to use better coding standards so you avoid future headaches. I use it on every JavaScript project I code.
An efficient and correct way to compare dates is:
Math.floor(date1.getTime() / 86400000) > Math.floor(date2.getTime() / 86400000);
It ignores the time part, it works for different timezones, and you can compare for equality == too. 86400000 is the number of milliseconds in a day (= 24*60*60*1000).
Beware that the equality operator == should never be used for comparing Date objects because it fails when you would expect an equality test to work because it is comparing two Date objects (and does not compare the two dates) e.g.:
> date1;
outputs: Thu Mar 08 2018 00:00:00 GMT+1300
> date2;
outputs: Thu Mar 08 2018 00:00:00 GMT+1300
> date1 == date2;
outputs: false
> Math.floor(date1.getTime() / 86400000) == Math.floor(date2.getTime() / 86400000);
outputs: true
Notes: If you are comparing Date objects that have the time part set to zero, then you could use date1.getTime() == date2.getTime() but it is hardly worth the optimisation. You can use <, >, <=, or >= when comparing Date objects directly because these operators first convert the Date object by calling .valueOf() before the operator does the comparison.
As I don't see here similar approach, and I'm not enjoying setting h/m/s/ms to 0, as it can cause problems with accurate transition to local time zone with changed date object (I presume so), let me introduce here this, written few moments ago, lil function:
+: Easy to use, makes a basic comparison operations done (comparing day, month and year without time.)
-: It seems that this is a complete opposite of "out of the box" thinking.
function datecompare(date1, sign, date2) {
var day1 = date1.getDate();
var mon1 = date1.getMonth();
var year1 = date1.getFullYear();
var day2 = date2.getDate();
var mon2 = date2.getMonth();
var year2 = date2.getFullYear();
if (sign === '===') {
if (day1 === day2 && mon1 === mon2 && year1 === year2) return true;
else return false;
}
else if (sign === '>') {
if (year1 > year2) return true;
else if (year1 === year2 && mon1 > mon2) return true;
else if (year1 === year2 && mon1 === mon2 && day1 > day2) return true;
else return false;
}
}
Usage:
datecompare(date1, '===', date2) for equality check,
datecompare(date1, '>', date2) for greater check,
!datecompare(date1, '>', date2) for less or equal check
Also, obviously, you can switch date1 and date2 in places to achieve any other simple comparison.
This JS will change the content after the set date here's the same thing but on w3schools
date1 = new Date()
date2 = new Date(2019,5,2) //the date you are comparing
date1.setHours(0,0,0,0)
var stockcnt = document.getElementById('demo').innerHTML;
if (date1 > date2){
document.getElementById('demo').innerHTML="yes"; //change if date is > set date (date2)
}else{
document.getElementById('demo').innerHTML="hello"; //change if date is < set date (date2)
}<p id="demo">hello</p> <!--What will be changed-->
<!--if you check back in tomorrow, it will say yes instead of hello... or you could change the date... or change > to <-->The date.js library is handy for these things. It makes all JS date-related scriping a lot easier.
This is the way I do it:
var myDate = new Date($('input[name=frequency_start]').val()).setHours(0,0,0,0);
var today = new Date().setHours(0,0,0,0);
if(today>myDate){
jAlert('Please Enter a date in the future','Date Start Error', function(){
$('input[name=frequency_start]').focus().select();
});
}
After reading this question quite same time after it is posted I have decided to post another solution, as I didn't find it that quite satisfactory, at least to my needs:
I have used something like this:
var currentDate= new Date().setHours(0,0,0,0);
var startDay = new Date(currentDate - 86400000 * 2);
var finalDay = new Date(currentDate + 86400000 * 2);
In that way I could have used the dates in the format I wanted for processing afterwards. But this was only for my need, but I have decided to post it anyway, maybe it will help someone
This works for me:
export default (chosenDate) => {
const now = new Date();
const today = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate()));
const splitChosenDate = chosenDate.split('/');
today.setHours(0, 0, 0, 0);
const fromDate = today.getTime();
const toDate = new Date(splitChosenDate[2], splitChosenDate[1] - 1, splitChosenDate[0]).getTime();
return toDate < fromDate;
};
In accepted answer, there is timezone issue and in the other time is not 00:00:00
Make sure you construct userDate with a 4 digit year as setFullYear(10, ...) !== setFullYear(2010, ...).
You can use some arithmetic with the total of ms.
var date = new Date(date1);
date.setHours(0, 0, 0, 0);
var diff = date2.getTime() - date.getTime();
return diff >= 0 && diff < 86400000;
I like this because no updates to the original dates are made and perfom faster than string split and compare.
Hope this help!
Comparing with setHours() will be a solution. Sample:
var d1 = new Date();
var d2 = new Date("2019-2-23");
if(d1.setHours(0,0,0,0) == d2.setHours(0,0,0,0)){
console.log(true)
}else{
console.log(false)
}
I know this question have been already answered and this may not be the best way, but in my scenario its working perfectly, so I thought it may help someone like me.
if you have date string as
String dateString="2018-01-01T18:19:12.543";
and you just want to compare the date part with another Date object in JS,
var anotherDate=new Date(); //some date
then you have to convert the string to Date object by using new Date("2018-01-01T18:19:12.543");
and here is the trick :-
var valueDate =new Date(new Date(dateString).toDateString());
return valueDate.valueOf() == anotherDate.valueOf(); //here is the final result
I have used toDateString() of Date object of JS, which returns the Date string only.
Note: Don't forget to use the .valueOf() function while comparing the dates.
more info about .valeOf() is here reference
Happy codding.
This will help. I managed to get it like this.
var currentDate = new Date(new Date().getFullYear(), new Date().getMonth() , new Date().getDate())
var fromdate = new Date(MM/DD/YYYY);
var todate = new Date(MM/DD/YYYY);
if (fromdate > todate){
console.log('False');
}else{
console.log('True');
}
if your date formate is different then use moment.js library to convert the format of your date and then use above code for compare two date
Example :
If your Date is in "DD/MM/YYYY" and wants to convert it into "MM/DD/YYYY" then see the below code example
var newfromdate = new Date(moment(fromdate, "DD/MM/YYYY").format("MM/DD/YYYY"));
console.log(newfromdate);
var newtodate = new Date(moment(todate, "DD/MM/YYYY").format("MM/DD/YYYY"));
console.log(newtodate);
You can use fp_incr(0). Which sets the timezone part to midnight and returns a date object.
Compare Date and Time:
var t1 = new Date(); // say, in ISO String = '2022-01-21T12:30:15.422Z'
var t2 = new Date(); // say, in ISO String = '2022-01-21T12:30:15.328Z'
var t3 = t1;
Compare 2 date objects by milliseconds level:
console.log(t1 === t2); // false - Bcos there is some milliseconds difference
console.log(t1 === t3); // true - Both dates have milliseconds level same values
Compare 2 date objects ONLY by date (Ignore any time difference):
console.log(t1.toISOString().split('T')[0] === t2.toISOString().split('T')[0]);
// true; '2022-01-21' === '2022-01-21'
Compare 2 date objects ONLY by time(ms) (Ignore any date difference):
console.log(t1.toISOString().split('T')[1] === t3.toISOString().split('T')[1]);
// true; '12:30:15.422Z' === '12:30:15.422Z'
Above 2 methods uses toISOString() method so you no need to worry about the time zone difference across the countries.
One option that I ended up using was to use the diff function of Moment.js. By calling something like start.diff(end, 'days') you can compare difference in whole numbers of days.
Works for me: I needed to compare a date to a local dateRange
let dateToCompare = new Date().toLocaleDateString().split("T")[0])
let compareTime = new Date(dateToCompare).getTime()
let startDate = new Date().toLocaleDateString().split("T")[0])
let startTime = new Date(startDate).getTime()
let endDate = new Date().toLocaleDateString().split("T")[0])
let endTime = new Date(endDate).getTime()
return compareTime >= startTime && compareTime <= endTime
As per usual. Too little, too late.
Nowadays use of momentjs is discouraged (their words, not mine) and dayjs is preferred.
One can use dayjs's isSame.
https://day.js.org/docs/en/query/is-same
dayjs().isSame('2011-01-01', 'date')
There are also a bunch of other units you can use for the comparisons: https://day.js.org/docs/en/manipulate/start-of#list-of-all-available-units
Using javascript you can set time values to zero for existing date objects and then parse back to Date. After parsing back to Date, Time value is 0 for both and you can do further comparison
let firstDate = new Date(mydate1.setHours(0, 0, 0, 0));
let secondDate = new Date(mydate2.setHours(0, 0, 0, 0));
if (selectedDate == currentDate)
{
console.log('same date');
}
else
{
console.log(`not same date`);
}
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