It amazes me that JavaScript's Date object does not implement an add function of any kind.
I simply want a function that can do this:
var now = Date.now();
var fourHoursLater = now.addHours(4);
function Date.prototype.addHours(h) {
// How do I implement this?
}
I would simply like some pointers in a direction.
Do I need to do string parsing?
Can I use setTime?
How about milliseconds?
Like this:
new Date(milliseconds + 4*3600*1000 /* 4 hours in ms */)?
This seems really hackish though - and does it even work?
JavaScript itself has terrible Date/Time API's. Nonetheless, you can do this in pure JavaScript:
Date.prototype.addHours = function(h) {
this.setTime(this.getTime() + (h*60*60*1000));
return this;
}
Date.prototype.addHours= function(h){
this.setHours(this.getHours()+h);
return this;
}
Test:
alert(new Date().addHours(4));
The below code will add 4 hours to a date (example, today's date):
var today = new Date();
today.setHours(today.getHours() + 4);
It will not cause an error if you try to add 4 to 23 (see the documentation):
If a parameter you specify is outside of the expected range, setHours() attempts to update the date information in the Date object accordingly
It is probably better to make the addHours method immutable by returning a copy of the Date object rather than mutating its parameter.
Date.prototype.addHours= function(h){
var copiedDate = new Date(this.getTime());
copiedDate.setHours(copiedDate.getHours()+h);
return copiedDate;
}
This way you can chain a bunch of method calls without worrying about state.
The version suggested by kennebec will fail when changing to or from DST, since it is the hour number that is set.
this.setUTCHours(this.getUTCHours()+h);
will add h hours to this independent of time system peculiarities.
Jason Harwig's method works as well.
Get a date exactly two hours from now, in one line.
You need to pass milliseconds to new Date.
let expiryDate = new Date(new Date().setHours(new Date().getHours() + 2));
or
let expiryDate2 = new Date(Date.now() + 2 * (60 * 60 * 1000) );
let nowDate = new Date();
let expiryDate = new Date(new Date().setHours(new Date().getHours() + 2));
let expiryDate2 = new Date(Date.now() + 2 * (60 * 60 * 1000) );
console.log('now', nowDate);
console.log('expiry', expiryDate);
console.log('expiry 2', expiryDate2);
You can use the Moment.js library.
var moment = require('moment');
foo = new moment(something).add(10, 'm').toDate();
I also think the original object should not be modified. So to save future manpower here's a combined solution based on Jason Harwig's and Tahir Hasan answers:
Date.prototype.addHours= function(h){
var copiedDate = new Date();
copiedDate.setTime(this.getTime() + (h*60*60*1000));
return copiedDate;
}
If you would like to do it in a more functional way (immutability) I would return a new date object instead of modifying the existing and I wouldn't alter the prototype but create a standalone function. Here is the example:
//JS
function addHoursToDate(date, hours) {
return new Date(new Date(date).setHours(date.getHours() + hours));
}
//TS
function addHoursToDate(date: Date, hours: number): Date {
return new Date(new Date(date).setHours(date.getHours() + hours));
}
let myDate = new Date();
console.log(myDate)
console.log(addHoursToDate(myDate,2))
There is an add in the Datejs library.
And here are the JavaScript date methods. kennebec wisely mentioned getHours() and setHours();
Check if it’s not already defined. Otherwise, define it in the Date prototype:
if (!Date.prototype.addHours) {
Date.prototype.addHours = function(h) {
this.setHours(this.getHours() + h);
return this;
};
}
This is an easy way to get an incremented or decremented data value.
const date = new Date()
const inc = 1000 * 60 * 60 // an hour
const dec = (1000 * 60 * 60) * -1 // an hour
const _date = new Date(date)
return new Date(_date.getTime() + inc)
return new Date(_date.getTime() + dec)
Another way to handle this is to convert the date to unixtime (epoch), then add the equivalent in (milli)seconds, then convert it back. This way you can handle day and month transitions, like adding 4 hours to 21, which should result in the next day, 01:00.
SPRBRN is correct. In order to account for the beginning/end of the month and year, you need to convert to Epoch and back.
Here's how you do that:
var milliseconds = 0; //amount of time from current date/time
var sec = 0; //(+): future
var min = 0; //(-): past
var hours = 2;
var days = 0;
var startDate = new Date(); //start date in local time (we'll use current time as an example)
var time = startDate.getTime(); //convert to milliseconds since epoch
//add time difference
var newTime = time + milliseconds + (1000*sec) + (1000*60*min) + (1000*60*60*hrs) + (1000*60*60*24*days);
var newDate = new Date(newTime); //convert back to date; in this example: 2 hours from right now
Or do it in one line (where variable names are the same as above:
var newDate =
new Date(startDate.getTime() + millisecond +
1000 * (sec + 60 * (min + 60 * (hours + 24 * days))));
For a simple add/subtract hour/minute function in JavaScript, try this:
function getTime (addHour, addMin){
addHour = (addHour ? addHour : 0);
addMin = (addMin ? addMin : 0);
var time = new Date(new Date().getTime());
var AM = true;
var ndble = 0;
var hours, newHour, overHour, newMin, overMin;
// Change form 24 to 12 hour clock
if(time.getHours() >= 13){
hours = time.getHours() - 12;
AM = (hours>=12 ? true : false);
}else{
hours = time.getHours();
AM = (hours>=12 ? false : true);
}
// Get the current minutes
var minutes = time.getMinutes();
// Set minute
if((minutes + addMin) >= 60 || (minutes + addMin) < 0){
overMin = (minutes + addMin) % 60;
overHour = Math.floor((minutes + addMin - Math.abs(overMin))/60);
if(overMin < 0){
overMin = overMin + 60;
overHour = overHour-Math.floor(overMin/60);
}
newMin = String((overMin<10 ? '0' : '') + overMin);
addHour = addHour + overHour;
}else{
newMin = minutes + addMin;
newMin = String((newMin<10 ? '0' : '') + newMin);
}
// Set hour
if((hours + addHour >= 13) || (hours + addHour <= 0)){
overHour = (hours + addHour) % 12;
ndble = Math.floor(Math.abs((hours + addHour)/12));
if(overHour <= 0){
newHour = overHour + 12;
if(overHour == 0){
ndble++;
}
}else{
if(overHour == 0){
newHour = 12;
ndble++;
}else{
ndble++;
newHour = overHour;
}
}
newHour = (newHour<10 ? '0' : '') + String(newHour);
AM = ((ndble + 1) % 2 === 0) ? AM : !AM;
}else{
AM = (hours + addHour == 12 ? !AM : AM);
newHour = String((Number(hours) + addHour < 10 ? '0': '') + (hours + addHour));
}
var am = (AM) ? 'AM' : 'PM';
return new Array(newHour, newMin, am);
};
This can be used without parameters to get the current time:
getTime();
Or with parameters to get the time with the added minutes/hours:
getTime(1, 30); // Adds 1.5 hours to current time
getTime(2); // Adds 2 hours to current time
getTime(0, 120); // Same as above
Even negative time works:
getTime(-1, -30); // Subtracts 1.5 hours from current time
This function returns an array of:
array([Hour], [Minute], [Meridian])
If you need it as a string, for example:
var defaultTime: new Date().getHours() + 1 + ":" + new Date().getMinutes();
I think this should do the trick
var nextHour = Date.now() + 1000 * 60 * 60;
console.log(nextHour)
You can even format the date in desired format using the moment function after adding 2 hours.
var time = moment(new Date(new Date().setHours(new Date().getHours() + 2))).format("YYYY-MM-DD");
console.log(time);
A little messy, but it works!
Given a date format like this: 2019-04-03T15:58
//Get the start date.
var start = $("#start_date").val();
//Split the date and time.
var startarray = start.split("T");
var date = startarray[0];
var time = startarray[1];
//Split the hours and minutes.
var timearray = time.split(":");
var hour = timearray[0];
var minute = timearray[1];
//Add an hour to the hour.
hour++;
//$("#end_date").val = start;
$("#end_date").val(""+date+"T"+hour+":"+minute+"");
Your output would be: 2019-04-03T16:58
The easiest way to do it is:
var d = new Date();
d = new Date(d.setHours(d.getHours() + 2));
It will add 2 hours to the current time.
The value of d = Sat Jan 30 2021 23:41:43 GMT+0500 (Pakistan Standard Time).
The value of d after adding 2 hours = Sun Jan 31 2021 01:41:43 GMT+0500 (Pakistan Standard Time).
I have two Time Stamps in the following Format:
Start Time - 2016-01-01 00:00:00
Finish Time - 2016-01-02 23:15:00
I need to calculate the number of hours between the two date times correct to two decimal places.
I need the result to be in the following format
Hrs = 47.25
This would be 23 hours and .25 of an hour not 25 mins, I do not need to round to the nearest 15 I only need to round to 2 decimal places.
Any Help shall be much appreciated. This data will then be inserted back into a cell in a DHTMLX grid.
FINAL SOLUTION
adminGrid.attachEvent("onEditCell",function(stage,rId,cInd,nValue,oValue){
if ((cInd == colStartTime || cInd == colFinishTime) && stage == 2) {
var startTime = new Date(adminGrid.cells(rId,colStartTime).getValue());
var finishTime = new Date(adminGrid.cells(rId,colFinishTime).getValue());
var Hrs = ((finishTime - startTime)/1000/60/60).toFixed(2);
adminGrid.cells(rId,colHrs).setValue(Hrs);
}
return true;
});
var startDate = new Date('2016-01-01 00:00:00');
var endDate = new Date('2016-01-02 23:15:00');
var time = endDate - startDate;
console.log(time/1000/60/60%24); //23.25
like this can calculate the hours span.
var date1 = new Date("2016-01-01 00:00:00");
var date2 = new Date("2016-01-02 23:15:00");
var diff = date2.getTime() - date1.getTime();
var Hrs = diff / (1000 * 60 * 60);
console.log(Hrs);//It's 47.25.
I've tried and got 47.25.
I am trying to get the current time difference in hours and minutes between now and 12pm (midday). If it is past 12pm on the current day it must then count down the hours onto the next day.
I have looked around here for a while now and have found many examples on getting date differences but and am unable to get a working solution for time so have been playing around with writing my own. However I am unable to getTime(); to get hours and minutes from the millisecond timestamp on my new dates and am unsure why exactly. Here is my code:
dateone = new Date();
datetwo = new Date();
datetwo = datetwo.setHours(12);
dateone = dateone.getTime();
datetwo = datetwo.getTime();
if(dateone > datetwo) {
var seconds = dateone - datetwo;
} else {
var seconds = datetwo - dateone;
}
var d = seconds;
var minutes=(d/(1000*60))%60;
var hours=(d/(1000*60*60))%24;
var minutesround=Math.floor(minutes);
var hoursround=Math.round(hours);
var endtime = 12;
alert(hours);
alert(minutes);
If anyone is able to spot a better way of doing this, or can suggest anything it would be greatly appreciated!
Thanks,
Simon
Try
var d = new Date(), midDay = new Date();
midDay.setHours(12);
midDay.setMinutes(0);
midDay.setSeconds(0);
if(d > midDay) {
midDay.setDate(midDay.getDate() + 1)
}
var diff = (midDay.getTime() - d.getTime()) / 1000;
var hrs = parseInt(diff / 3600);
diff = diff % 3600;
var minutes = parseInt(diff / 60);
console.log(hrs, minutes)
Demo: Fiddle
I have this time stamp format for each car in my map:
2012-12-11T03:51:43+03:00
I want to extract the number of hours from it according to current time.
I don't know how to parse this string then compare it to current time.
Any Idea ?
something like:
var
d1 = new Date('2012-12-11T03:51:43+03:00'),
d2 = new Date;
console.log(
(d2 - d1) / 3600000
);
You need to first fix the timestamp for other browsers than Chrome
javascript date.parse difference in chrome and other browsers
DEMO
var noOffset = function(s) {
var day= s.slice(0,-5).split(/\D/).map(function(itm){
return parseInt(itm, 10) || 0;
});
day[1]-= 1;
day= new Date(Date.UTC.apply(Date, day));
var offsetString = s.slice(-5)
var offset = parseInt(offsetString,10)/100;
if (offsetString.slice(0,1)=="+") offset*=-1;
day.setHours(day.getHours()+offset);
return day.getTime();
}
alert(parseInt((new Date().getTime()-noOffset(yourTimeStamp))/3600000))
I want to adjust the Date object to always be 4 hours offset. How would I achieve this?
var d = new Date();
// d would be 4 hours in the past
Something like this:
d.setHours(d.getHours()-4);
Date.withOffset = function( offset ){
var r = new Date();
r.setHours(r.getHours()+offset);
return r;
};
var d = Date.withOffset( -4 )
// d would be 4 hours in the past
You may come up with a better name.
If you wish to break all javascript on your page you may of course use:
Date = function () {
var old = Date;
function broken() {
var r = new old();
r.setHours(r.getHours()-4);
return r;
}
broken.fix = function () {
Date = old;
};
return broken;
}();
You can then fix it by calling Date.fix()
You can create a date object with a particular date. Just subtract the correct milliseconds from the current time and pass that to the date function:
var d = new Date(new Date().getTime() - 1000*60*60*4);
or you can manually set the hours
var d = new Date();
d.setHours((12 + (d.getHours() - 4))%12)