Develop Reference

how to check the diffrence between dates

I created a function to check the difference between a particular date and the current date, everything is working perfectly for past dates. But, when it comes to future dates, it gives the correct difference eg. the 18th of May is two days after the 16th of May, so the difference is 2, but I don't know if it's two days before or two days after. I cannot differentiate between future dates and past dates, whether the date is in the past or in the future.
here is my code:
function GetDateDiff(previousDate, previousTime) {
let today = new Date();
let dd = String(today.getDate()).padStart(2, "0");
let mm = String(today.getMonth() + 1).padStart(2, "0"); //January is 0!
let yyyy = today.getFullYear();
let currentDate = mm + "/" + dd + "/" + yyyy; // this will give you the current date
let previousMinutes = previousTime.split(":")[1];
let previousSeconds = previousTime.split(":")[2];
let previousHours = previousTime.split(":")[0];
let timePeriod = "seconds"; // timePeriod is the current unit of mesearement whether in seconds hours or days
let timeInNumber = "0"; //timeInNumber is the number infront of the timeperiod eg the 40 in 40 minites is the timeInNumber
let dateObj = new Date();
// this is to set the appropriate seconds, minutes and hours
if (currentDate == previousDate) {
if (dateObj.getHours() == previousHours) {
if (dateObj.getMinutes() == previousMinutes) {
timeInNumber = dateObj.getSeconds() - previousSeconds;
timePeriod = "Second";
} else {
timeInNumber = dateObj.getMinutes() - previousMinutes;
timePeriod = "Minute";
}
} else {
timeInNumber = dateObj.getHours() - previousHours;
timePeriod = "Hour";
// timePeriod =dateObj.getHours();
}
} else {
const previousDateDifferential = new Date(previousDate);
const currentDateDifferential = new Date(currentDate);
const diffrenceInDate = Math.abs(
currentDateDifferential - previousDateDifferential
);
// this is to calculate the diffrence in days, weeks, months and years
const diffDays = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24));
const diffWeeks = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24 * 7));
const diffMonths = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24 * 7 * 4));
const diffyears = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24 * 7 * 4 * 12));
// this is to set the appropriate days, weeks, months and years
if (diffDays <= 30) {
timeInNumber = diffDays;
timePeriod = "Day";
} else if (diffDays > 30 && diffWeeks <= 4) {
timeInNumber = diffWeeks;
timePeriod = "Week";
} else if (diffWeeks > 4 && diffMonths <= 12) {
timeInNumber = diffMonths - 2;
timePeriod = "Month";
} else if (diffMonths > 12) {
timeInNumber = diffyears - 1;
timePeriod = "Year";
}
}
if (timeInNumber > 1) {
timePeriod += "s"// this is to ad 's' at the end of the time period if the time period is more than 1
}
return `${timeInNumber} ${timePeriod} Ago`;
}
if I write GetDateDiff("05/14/2022", "00:00:00") // result will be 2 days ago
if I write GetDateDiff("05/18/2022", "00:00:00") // result will still be 2 days ago, how can i make it 2 days later or check that the date is in the future

The best tip was given already: use > and < to compare dates. Here is an example to get you started:
// function GetDateDiff to get the difference to the current date including negative values
function GetDateDiff(date) {
// get current date
var currentDate = new Date();
// get the difference between the current date and the date passed in
var diff = date.getTime() - currentDate.getTime();
// Build string prefix for negative and positive dates
var diffString = diff < 0 ? "In the Past: " : "In the Future: ";
// get the absolute value of the difference
diff = Math.abs(diff);
// get the days, hours, minutes, and seconds from the difference
var days = Math.floor(diff / (1000 * 60 * 60 * 24));
var hours = Math.floor((diff % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((diff % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((diff % (1000 * 60)) / 1000);
// return the difference in days, hours, minutes, and seconds
return diffString + days + " days, " + hours + " hours, " + minutes + " minutes, " + seconds + " seconds";
}
// example usage
var date = new Date(2020, 0, 1, 0, 0, 0, 0);
var diff = GetDateDiff(date);
alert(diff);
var date = new Date(2024, 0, 1, 0, 0, 0, 0);
var diff = GetDateDiff(date);
alert(diff);

function GetDateDiff(previousDate, previousTime) {
let today = new Date();
let dd = String(today.getDate()).padStart(2, "0");
let mm = String(today.getMonth() + 1).padStart(2, "0"); //January is 0!
let yyyy = today.getFullYear();
let currentDate = mm + "/" + dd + "/" + yyyy; // this will give you the current date
let previousMinutes = previousTime.split(":")[1];
let previousSeconds = previousTime.split(":")[2];
let previousHours = previousTime.split(":")[0];
let timePeriod = "seconds"; // timePeriod is the current unit of mesearement whether in seconds hours or days
let timeInNumber = "0"; //timeInNumber is the number infront of the timeperiod eg the 40 in 40 minites is the timeInNumber
let timeWord = "Ago"
let dateObj = new Date();
// this is to set the appropriate seconds, minutes and hours
if (currentDate == previousDate) {
if (dateObj.getHours() == previousHours) {
if (dateObj.getMinutes() == previousMinutes) {
timeInNumber = dateObj.getSeconds() - previousSeconds;
timePeriod = "Second";
} else {
timeInNumber = dateObj.getMinutes() - previousMinutes;
timePeriod = "Minute";
}
} else {
timeInNumber = dateObj.getHours() - previousHours;
timePeriod = "Hour";
// timePeriod =dateObj.getHours();
}
}
else {
const previousDateDifferential = new Date(previousDate);
const currentDateDifferential = new Date(currentDate);
const diffrenceInDate = Math.abs(
currentDateDifferential - previousDateDifferential
);
// this is to calculate the diffrence in days, weeks, months and years
const diffDays = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24));
const diffWeeks = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24 * 7));
const diffMonths = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24 * 7 * 4));
const diffyears = Math.ceil(diffrenceInDate / (1000 * 60 * 60 * 24 * 7 * 4 * 12));
// this is to set the appropriate days, weeks, months and years
if (diffDays <= 30) {
timeInNumber = diffDays;
timePeriod = "Day";
} else if (diffDays > 30 && diffWeeks <= 4) {
timeInNumber = diffWeeks;
timePeriod = "Week";
} else if (diffWeeks > 4 && diffMonths <= 12) {
timeInNumber = diffMonths - 2;
timePeriod = "Month";
} else if (diffMonths > 12) {
timeInNumber = diffyears - 1;
timePeriod = "Year";
}
if (currentDate < previousDate) {
timeWord = "Later"
}else {
timeWord = "Ago"
}
}
if (timeInNumber > 1) {
timePeriod += "s"// this is to ad 's' at the end of the time period if the time period is more than 1
}
return `${timeInNumber} ${timePeriod} ${timeWord}`;
}
GetDateDiff("05/14/2022", "00:00:00") // result will be 2 days ago
GetDateDiff("05/18/2022", "00:00:00") // result will be 2 days later

Time calculation with milliseconds in JS

I want to find difference between two time with milliseconds value in Javascript.
As you can see below snapshot, where I calculated two time values in Excel.
My expectation exactly same calculated value with JS code.
I tried some code snippet but I got slightly difference in seconds.
var d1 = '2020-12-15 01:00:23.788';
var d2 = '2020-12-15 01:00:55.482';
var date1 = new Date(d1);
var date2 = new Date(d2);
//date2 += 500;
//date2 = new Date(date2);
//date2.setMilliseconds(5);
var date1_ms = date1.getTime();
var date2_ms = date2.getTime();
// Calculate the difference in milliseconds
var difference_ms = date2_ms - date1_ms;
//take out milliseconds
difference_ms = difference_ms / 1000;
var seconds = Math.floor(difference_ms % 60);
difference_ms = difference_ms / 60;
var minutes = Math.floor(difference_ms % 60);
difference_ms = difference_ms / 60;
var hours = Math.floor(difference_ms % 24);
var demo = hours + ' hours, ' + minutes + ' minutes, and ' + seconds + ' seconds.' + difference_ms;
document.getElementById("demo").innerHTML = demo;
<h2>JavaScript new Date()</h2>
<p>new Date() creates a new date object with the current date and time:</p>
<p id="demo"></p>
OUTPUT:
new Date() creates a new date object with the current date and time:
0 hours, 0 minutes, and 31 seconds.0.008803888888888889

JS does the same when correctly implemented
I tried with more interesting times
// Excel: 02:10:55,482 - 01:09:23,788 = 01:01:31,694
const fmtTime = date => {
const hours = `0${date.getHours() - 1}`.slice(-2);
const minutes = `0${date.getMinutes()}`.slice(-2);
const seconds = `0${date.getSeconds()}`.slice(-2);
const ms = `00${date.getMilliseconds()}`.slice(-3);
return `${hours}:${minutes}:${seconds}.${ms}`
}
const from = "01:09:23,788"
const to = "02:10:55.482"
const re = /(\d{2}):(\d{2}):(\d{2}).(\d{3})/;
const [m1, fromhh, frommm, fromss, fromms] = from.match(re);
const [m2, tohh, tomm, toss, tomms] = to.match(re);
// method one
let d = new Date()
d.setHours(fromhh, frommm, fromss, fromms)
const fromTime = d.getTime()
d.setHours(tohh, tomm, toss, tomms)
const toTime = d.getTime()
const diffInMS1 = toTime - fromTime
console.log(diffInMS1)
d = new Date(diffInMS1);
console.log(fmtTime(d))
// Method 2 - Note I need to cast to int where I only add (+fromms)
let fromMS = (fromhh * 60 * 60 * 1000) + (frommm * 60 * 1000) + (fromss * 1000) + +fromms;
let toMS = (tohh * 60 * 60 * 1000) + (tomm * 60 * 1000) + (toss * 1000) + +tomms;
const diffInMS2 = toMS - fromMS;
console.log(diffInMS2)
d = new Date(diffInMS2);
console.log(fmtTime(d))

function splitInNumberArray(str) {
return str
.replace(/(:|\.)/g, " ")
.split(" ")
.map((x) => parseInt(x));
}
function convertToMilliseconds(timeArray) {
return (
timeArray[0] * 60 * 60 * 1000 +
timeArray[1] * 60 * 1000 +
timeArray[2] * 1000 +
timeArray[3]
);
}
function msToTime(duration) {
var milliseconds = parseInt((duration % 1000) / 100),
seconds = Math.floor((duration / 1000) % 60),
minutes = Math.floor((duration / (1000 * 60)) % 60),
hours = Math.floor((duration / (1000 * 60 * 60)) % 24);
hours = hours < 10 ? "0" + hours : hours;
minutes = minutes < 10 ? "0" + minutes : minutes;
seconds = seconds < 10 ? "0" + seconds : seconds;
return hours + ":" + minutes + ":" + seconds + "." + milliseconds;
}
// This function is taken from https://stackoverflow.com/questions/19700283/how-to-convert-time-milliseconds-to-hours-min-sec-format-in-javascript
function parseDuration(duration) {
let remain = duration;
let hours = Math.floor(remain / (1000 * 60 * 60));
remain = remain % (1000 * 60 * 60);
let minutes = Math.floor(remain / (1000 * 60));
remain = remain % (1000 * 60);
let seconds = Math.floor(remain / 1000);
remain = remain % 1000;
let milliseconds = remain;
return {
hours,
minutes,
seconds,
milliseconds,
};
}
function minTwoDigits(n) {
return (n < 10 ? "0" : "") + n;
}
//***************************************
const time1 = "01:00:55.482";
const time2 = "01:00:23.788";
const numberArray1 = splitInNumberArray(time1);
const numberArray2 = splitInNumberArray(time2);
const msTime1 = convertToMilliseconds(numberArray1);
const msTime2 = convertToMilliseconds(numberArray2);
const diff = msTime1 - msTime2;
const { hours, minutes, seconds, milliseconds } = parseDuration(diff);
console.log(
`${time1} - ${time2} = ${minTwoDigits(hours)}:${minTwoDigits(
minutes
)}:${minTwoDigits(seconds)}.${milliseconds}`
);

How can I get correct remaining Hours from two times in javascript?

I'm trying to calculate the time remaining hours based on the difference of two times passing parameter in my function. I am passing NetHrs , time2 as an argument in a javascript function but getting wrong remaining hours after calculation
I am passing NetHrs 7.30(intime), WorkHrs(outtime) as 3.22 Then the result should be given as 4.08. But it gives 4.80
If I am passing NetHrs 7.30 WorkHrs as 3.10 Then the result should be 4.20. This gives correct result
But in first case my function gives wrong result. Please help
Here is my function
function GetNetHrs(inTime, outTime) {
inTime = inTime.replace('.', ':');
outTime = outTime.replace('.', ':');
var indate = new Date("01/01/2018 " + inTime + ":00");
var outdate = new Date("01/01/2018 " + outTime + ":00");
var diff = indate.getTime() - outdate.getTime();
var msec = diff;
var hh = Math.floor(msec / 1000 / 60 / 60);
console.log(msec / 1000 / 60 / 60);
msec -= hh * 1000 * 60 * 60;
var mm = Math.floor(msec / 1000 / 60);
msec -= mm * 1000 * 60;
var ss = Math.floor(msec / 1000);
msec -= ss * 1000;
var netHrsStr = hh + "." + mm;
return parseFloat(netHrsStr);
}
console.log(GetNetHrs("7.30","3.22"))
console.log(GetNetHrs("7.30","3.10"))

You need to ensure your mm value is 0n not n - you can use padStart for that., but you must first turn it back to a string.
function GetNetHrs(inTime, outTime) {
inTime = inTime.replace('.', ':');
outTime = outTime.replace('.', ':');
var indate = new Date("01/01/2018 " + inTime + ":00");
var outdate = new Date("01/01/2018 " + outTime + ":00");
var diff = indate.getTime() - outdate.getTime();
var msec = diff;
var hh = Math.floor(msec / 1000 / 60 / 60);
console.log(msec / 1000 / 60 / 60);
msec -= hh * 1000 * 60 * 60;
var mm = Math.floor(msec / 1000 / 60);
msec -= mm * 1000 * 60;
var ss = Math.floor(msec / 1000);
msec -= ss * 1000;
var netHrsStr = hh + "." + mm.toString().padStart(2,"0");
return parseFloat(netHrsStr);
}
console.log(GetNetHrs("7.30","3.22"))
console.log(GetNetHrs("7.30","3.10"))

I don't know what's wrong with your function but here's how I do it:
function diff_hours(dt2, dt1)
{
var diff =(dt2.getTime() - dt1.getTime()) / 1000;
diff /= (60 * 60);
return Math.abs(Math.round(diff));
}
this function Write will get time differences in hours between two dates.
now if you want to test it here's an example:
dt1 = new Date(2014,10,2);
dt2 = new Date(2014,10,3);
console.log(diff_hours(dt1, dt2));
dt1 = new Date("October 13, 2014 08:11:00");
dt2 = new Date("October 13, 2014 11:13:00");
console.log(diff_hours(dt1, dt2));
output:
24
3
If you want to learn more about it ClickMe

javascript - get the date of next day in week?

how do I get, for example, the date of next monday and the time 5:30PM, and calculate the difference between current date and time and that date and time?
if I run it now at 8/28/2020 17:35, it should give me 8/31/2020 17:30 and the difference 2 days 23 hours 55 minutes.

I hope this help:
// takes dayIndex from Sunday(0) to Saturday(6)
const getNextDay = (dayIndex) => {
const today = new Date();
today.setDate(
today.getDate() + ((dayIndex - 1 - today.getDay() + 7) % 7) + 1
);
today.setHours(17, 30, 00);
return today;
};
const getTimeleft = (dateNow, dateFuture) => {
let seconds = Math.floor((dateFuture - dateNow) / 1000);
let minutes = Math.floor(seconds / 60);
let hours = Math.floor(minutes / 60);
let days = Math.floor(hours / 24);
hours = hours - days * 24;
minutes = minutes - days * 24 * 60 - hours * 60;
seconds = seconds - days * 24 * 60 * 60 - hours * 60 * 60 - minutes * 60;
return `${days} days ${hours} hours ${minutes} minutes`;
};
const now = new Date();
const nextMonday = getNextDay(1);
const timeleft = getTimeleft(now, nextMonday);
console.log(nextMonday.toLocaleString());
console.log(timeleft);

You could use moment.js, it's a very useful library when it comes to dates:
<script src="https://momentjs.com/downloads/moment.js"></script>
<script>
const today = moment();
const nextMonday = moment().add(1, 'weeks').isoWeekday(1);
nextMonday.set({'hour': 17, 'minute': 30, 'seconds': 0});
console.log(nextMonday.toString());
const duration = moment.duration(nextMonday.diff(today));
const days = duration.asDays();
const hours = (days - Math.floor(days)) * 24;
const minutes = (hours - Math.floor(hours)) * 60;
console.log("days", Math.floor(days));
console.log("hours", Math.floor(hours));
console.log("minutes", Math.floor(minutes));
</script>

Here is the working example:
function nextWeekMonday(date)
{
var diff = date.getDate() - date.getDay() + (date.getDay() === 0 ? -6 : 1);
var currWeekMonday = new Date(date.setDate(diff));
return new Date(currWeekMonday.getTime() + 7 * 24 * 60 * 60 * 1000);
}
function getDateDifference(current, future) {
// get total seconds between the times
var delta = Math.abs(future - current) / 1000;
// calculate (and subtract) whole days
var days = Math.floor(delta / 86400);
delta -= days * 86400;
// calculate (and subtract) whole hours
var hours = Math.floor(delta / 3600) % 24;
delta -= hours * 3600;
// calculate (and subtract) whole minutes
var minutes = Math.floor(delta / 60) % 60;
delta -= minutes * 60;
// what's left is seconds
var seconds = delta % 60;
return `${days} Days, ${hours} Hours, ${minutes} Minutes, ${seconds} Seconds`;
}
var curr = new Date; // get current date
var nextMonday = nextWeekMonday(curr);
console.log(getDateDifference(curr, nextMonday));

Reset Countdown

I found a countdown that is suitable for my web-project. I want that the countdown restarts every Friday at 9 am. Could someone give me a hint? Here is the code:
(function(){
const days = document.getElementById("days");
const hours = document.getElementById("hours");
const minutes = document.getElementById("minutes");
const seconds = document.getElementById("seconds");
const currentDate = new Date().getFullYear();
const concertDate = new Date(`June 19 ${currentDate} 09:00:00`);
function updateCountdown() {
const currentTime = new Date();
const diff = concertDate - currentTime;
const d = Math.floor(diff / 1000 / 60 / 60 / 24);
const h = Math.floor(diff / 1000 / 60 / 60) % 24;
const m = Math.floor(diff / 1000 / 60) % 60;
const s = Math.floor(diff / 1000) % 60;
days.innerHTML = d;
hours.innerHTML = h < 10 ? "0" + h : h;
minutes.innerHTML = m < 10 ? "0" + m : m;
seconds.innerHTML = s < 10 ? "0" + s : s;
}
setInterval(updateCountdown, 1000);
})();

Here is how I would do it. In the countdown function, add an if statement that checks whether the diff <= 0 - if it is (countdown expired), simply add one week of time to the concertDate, and the new countdown starts.
For this to work, firstly you have to change the concertDate declaration to let concertDate to allow it to be changed later on. And also, you need to use .getTime() for the concert that will give you the time of that date in miliseconds (this makes adding one week of time at the end possible).
(function(){
const days = document.getElementById("days");
const hours = document.getElementById("hours");
const minutes = document.getElementById("minutes");
const seconds = document.getElementById("seconds");
const currentDate = new Date().getFullYear();
let concertDate = new Date(`June 19 ${currentDate} 09:00:00`).getTime();
function updateCountdown() {
const currentTime = new Date();
const diff = concertDate - currentTime;
const d = Math.floor(diff / 1000 / 60 / 60 / 24);
const h = Math.floor(diff / 1000 / 60 / 60) % 24;
const m = Math.floor(diff / 1000 / 60) % 60;
const s = Math.floor(diff / 1000) % 60;
days.innerHTML = d;
hours.innerHTML = h < 10 ? "0" + h : h;
minutes.innerHTML = m < 10 ? "0" + m : m;
seconds.innerHTML = s < 10 ? "0" + s : s;
if (diff <= 0) {
concertDate = concertDate + (1000 * 3600 * 24 * 7); //add one week to concert date
}
}
setInterval(updateCountdown, 1000);
})();
Hope that helps!

You can use [cron]: https://www.npmjs.com/package/cron;
Your cron time should be like 0 9 * * 5