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Converting date JavaScript

I'm currently populating a table with data from a soap web service, the date comes as a string (example 44250). I created a function to format it into a yyyy/mm/dd format.
Outside the loop I have this function:
Date.prototype.addDays = function (days) {
var date = new Date(this.valueOf());
date.setDate(date.getDate() + days);
return date;
};
Inside the loop I have:
else if (detailsItem == details[i].children[1].innerHTML) {
const dbDays = days[i].innerHTML;
const daysInt = parseInt(dbDays, 0);
const newDate = firstDate.addDays(daysInt);
// Format the date to a readable value
const partsDate = {
date: newDate.getDate(),
month: newDate.getMonth() + 1,
year: newDate.getYear() + 1900,
};
finalDate = `${partsDate.date}/${partsDate.month}/${partsDate.year}`;
const td = document.createElement("td");
td.textContent = finalDate;
tr.appendChild(td);
}
the else if is just checking when to add the date to the table while populating it.
I now need to send a request to the service using the date again but in the previous format, but the date has to be in the same row as the button click, the service only accepts the string format of the date, I'm currently stuck and unsure on how to format it back.
This is the button click function which has to then format the date back to a format such as 44250.
btn.onclick = function () {
// Loops through the table to find the slot and date when clicking the button on the same row
var tableRow = document.getElementById("booking-table"),
rIndex;
for (var i = 0; i < tableRow.rows.length; i++) {
tableRow.rows[i].onclick = function () {
rIndex = this.rowIndex;
bookingDay = this.cells[1].innerHTML;
bookingSlot = this.cells[2].innerHTML;
console.log(bookingSlot, bookingDay);
};
}
Any help on how to accomplish this would be appreciated.

The value "44250" looks like the number of days since 31 Dec 1899 (the epoch), which means a value of "1" converts to 1 Jan 1900. If that's correct, you can create a Date from it using:
let dbDays = '44250';
let date = new Date(1900, 0, dbDays); // 24 Feb 2021
In this algorithm, 1 is 1 Jan 1900 and 0 is 31 Dec 1899.
You can convert it back to an epoch offset using the reverse algorithm:
let dbDays = Math.round((date.getTime() - new Date(1899, 11, 31) / 8.64e7);
Which gets the difference in ms since the date and the epoch, then divides by ms in one day and rounds it to account for possible daylight saving effects where days aren't exactly 24 hours long. This method only works for whole days, it doesn't work for partial days.
The algorithm might be out by a day if 1 Jan 1900 should be 0 rather than 1, just adjust the base dates used in the functions.
Simple functions to go from dbDate to Date instance and back are:
// Convert epoch days to Date
function toDate(dbDays) {
return new Date(1900, 0, +dbDays);
}
// Convert Date to epoch days
function toDBDays(date) {
return Math.round((date - new Date(1899,11,31)) / 8.64e7);
}
// Format date as dd/mm/yyyy
function formatDate(d) {
let z = n => ('0'+n).slice(-2);
return z(d.getDate()) + '/' + z(d.getMonth()+1) + '/' + d.getFullYear();
}
// Parse date in d/m/y format, any non-digit separator
function parseDate(s) {
let [d,m,y] = s.split(/\D/);
return new Date(y, m - 1, d)
}
// Example
let dbDays = '44250';
let d1 = toDate(dbDays); // 24 Feb 2021
let ts = formatDate(d1); // 24/02/2021
let d2 = parseDate(ts); // date object
console.log(dbDays + ' to Date: ' + ts);
console.log(ts + ' to dbDays: ' + toDBDays(d2));
PS Given the epoch won't change, instead of creating a date for 31 Dec 1899 and getting its time value, the constant -2209111200000 can be used.
Notes on your code:
const daysInt = parseInt(dbDays, 0);
The second argument to parseInt is a radix or base to use for conversion to number. The value 0 is replaced with 10 (the default radix), so the above is equivalent to:
const daysInt = parseInt(dbDays, 10);
Then there is:
const partsDate = {
date: newDate.getDate(),
month: newDate.getMonth() + 1,
year: newDate.getYear() + 1900,
};
The getYear method returns a 2 digit year, it's not recommended and is supported mostly for historic reasons, use getFullYear instead.
Using an object for temporary storage is not really optimal, just use variables:
let date = newDate.getDate(),
month = newDate.getMonth() + 1,
year = newDate.getFullYear();
Note that this doesn't pad single digit days or months with leading zeros so will produce timestamps like 1/1/2021 instead of 01/01/2021.

You can use momentjs to convert the date easier: https://momentjs.com/ ,
about the use of the date after you pass that value to the html, can you store that value on some global variable,sesion or localstorage? and then use it later? to call again the soap service? i'm asumming your working on a web page, cause your using html :)

How to exclude weekends in date object in Javascript

I'm facing issue with excluding weekend dates in JavaScript.For my business requirement I want to exclude 3 days from date object Friday, Saturday and Sunday in every week.What I need here is the values of Friday should display as Monday, Saturday as Tuesday and Sunday as Wednesday. I'm able to do this.
The issue that I'm facing here is when we run the above example the a[0] value should be 21-SEP-2017 but I'm getting 20-SEP-2017 and remaining array values should not change. So please do help me out in resolving this issue
var a = ["21-SEP-2017", "22-SEP-2017", "23-SEP-2017", "24-SEP-2017", "25-SEP-2017"];
for (i = 0; i < a.length; i++) {
var startDate = a[i];
startDate = new Date(startDate.replace(/-/g, "/"));
var endDate = "",
noOfDaysToAdd = 1;
var count = 0;
endDate = new Date(startDate.setDate(startDate.getDate()));
if (startDate.getDay() != 0 && startDate.getDay() != 5 && startDate.getDay() != 6) {
endDate = new Date(startDate.setDate(startDate.getDate() + i - 1));
} else {
startDate.setDate(startDate.getDate() + 3)
endDate = new Date(startDate.setDate(startDate.getDate()));
}
console.log(endDate); //You can format this date as per your requirement
}

Your code seems not finished: the variables noOfDaysToAdd and count are never used, and if they were, they would be reset in every iteration of the loop, which cannot be the purpose.
That your output shows 20 September is because you did not output a stringified version of the date, but the date object itself, and then console.log will display the date as a UTC date (notice the time part matches the timezone difference). Instead use .toString() or another way to turn the date to a localised string.
Here is how you could do it:
function toDate(s) {
return new Date(s.replace(/-/g, '/'));
}
function toStr(dt) {
var months = ["JAN","FEB","MAR","APR","MAY","JUN",
"JUL","AUG","SEP","OCT","NOV","DEC"];
return [('0'+dt.getDate()).substr(-2), months[dt.getMonth()], dt.getFullYear()]
.join('-');
}
var a = ["21-SEP-2017", "22-SEP-2017", "23-SEP-2017", "24-SEP-2017", "25-SEP-2017"],
add = 0;
var result = a.map(toDate).map(dt => {
dt.setDate(dt.getDate()+add);
var move = [0, 6, 5].indexOf(dt.getDay()) + 1;
if (move) {
add += move;
dt.setDate(dt.getDate()+move);
}
return dt;
}).map(toStr);
console.log(result);

date object doesn't seem to be accurate when compared to today's date

I have this function that takes todays date and compares it to two weeks out. when it's less than or equal to the current date, it's supposed to add a class. However if it's today's date, it's not working. Otherwise it's working fine. Any ideas? Thanks
publicMethods.campaignEndDateAlert = function (dateString) {
if (!dateString) {
return dateString
};
var currentDate = new Date ();
var twoWeeks = new Date ();
twoWeeks.setDate(currentDate.getDate() + 14);
var inputDate = new Date(dateString);
// This is the part that doesn't seem to work - the first part of this if statement
if ((inputDate >= currentDate) && (inputDate <= twoWeeks)) {
dateString = '<span class="red">' + ax.Utils.RFCFormat(dateString, { excludeTime: true }) + '</span>';
} else {
dateString = ax.Utils.RFCFormat(dateString, { excludeTime: true })
};
return dateString;
};

Due to the information you provided:
You said that if it is today's date it doesn't work as expected. That is because new Date() will provide a date object with today's date and time. IF the value of dateString is something like "07-13-2017" without the time, you will need to strip the time out of the currentDate object if you expect inputDate >= currentDate to be true. Try using currentDate.setHours(0, 0, 0, 0); before comparing to inputDate.

JavaScript loop through Json dates

I'm trying to use JavaScript to loop through a json file which has time periods (starting date/time and ending date/time), and check if now (current date time) falls between any time period in such list.
Following is my code, but can't get where I'm wrong. Any help?
<html>
<script type="text/javascript">
var data = {
"period": {
"startend": [{
"startDate": "2015-11-17 15:43:37",
"endDate": "2015-11-18 19:43:37"
}, {
"startDate": "2015-12-17 19:43:37",
"endDate": "2016-01-17 19:43:37"
}, {
"startDate": "2015-04-17 19:43:37",
"endDate": "2015-04-18 19:43:37"
}]
}
}
var periodArray = data.period.startend;
var curDate = new Date();
var datetime = curDate.getFullYear() + '-' + curDate.getMonth() + '-' + curDate.getDate() + ' ' + curDate.getHours() + ':' + curDate.getMinutes() + ':' + curDate.getSeconds();
for (i = 0; i < periodArray.length ; i++) {
var obj = periodArray[i]
if (datetime > obj.startDate && datetime < obj.endDate){
alert('Falls within period');
} else {
alert('Not within any period');
}
}
</script>

The basic idea is to convert the date strings to actual Date objects so they can be compared with the current date (new Date()). Let's begin by defining a helper function that when initialized, closes over the current date, producing a function that takes a start date and an end date, either in String or in Date form, and returns true if and only if the closed over current date is in the range.
Definition.
// () -> (([String|Date] * [String|Date]) -> Boolean)
// When initialized, closes over the current date and returns
// a predicate on String or Date objects.
function includesNow() {
var curDate = new Date();
return function(start, end) {
var startDate = (typeof start === "string")
? new Date(start) : start;
var endDate = (typeof end === "string")
? new Date(end) : end;
return (curDate > startDate) && (curDate < endDate);
};
}
Usage.
With the help of the helper function, we can then pretty easily filter the "current" dates:
// Get the list of (date string) objects.
var allDates = data.period.startend;
// Capture the current date, returning the date range comparator.
var comparator = includesNow();
// Get the list of those (date string) objects `obj`
// that satisfy `comparator(obj.startDate, obj.endDate) === true`.
var currentDates = allDates.filter(function(obj) {
return comparator(obj.startDate, obj.endDate);
});
// This is a function of current date, so will be empty at some point.
currentDates[0];
// => Object {startDate: "2015-11-17 15:43:37", endDate: "2015-11-18 19:43:37"}
If you know your objects will always be Strings and never actual Date objects, then you can simplify includesNow considerably. If you're interested in the closed range be sure to replace > and < with ≥ and ≤, respectively.

JSON date is not a date object. It's a string. You're trying to compare a Date obj to a String.
If the JSON date was an ISO formatted date you could do :
var dateStr = JSON.parse(date);
var realDate = new Date(dateStr);
realDate would now have a js date object. Unfortunately in your example the startDate and endDate are not ISO strings.
This would be the easiest/cleanest solution. Otherwise you could always get the JSON date strings and break them apart with substring() and convert the years/months/days with Number(); and then compare them that way?

Time conversion to ISO string is not correct with text field displayed

I have a text field in an MVC application that displays the date and time. The date is created using a datepicker and the time I add to the text field.
An example of the text is as follows:
10/23/2015 12:00 AM
I want to create a Date object with this time in ISO 8601 format. The date will be used to create an event in a fullcalendar jquery plugin.
When I try to create the Date object, the ISO string is:
2015-10-23T04:00:00.000Z
It should be 2015-10-23T00:00:00.000Z to represent midnight on that day.
This is my code:
<label id="schedule_start_date_lbl">Start Date: </label>
<input id="schedule_start_date" type="text" />
var startDayIndex = getDayIndex($('#rotation_start_time_txt').val());
$("#schedule_start_date").datepicker({
minDate: 0,
beforeShowDay: function (date) { return [date.getDay() == startDayIndex, ""] },
onSelect: function (dateText) {
$('#schedule_end_date').datepicker('option', 'minDate', dateText);
},
onClose: function (selectedDate) {
var rotation_txt = $('#rotation_start_time_txt').val();
var time = rotation_txt.substr(rotation_txt.indexOf(',') + 1);
$(this).val(selectedDate + time.toString(' HH:mm tt').toString());
}
});
$("#rotation_schedule_btn").click(function () {
//text value in schedule_start_date is: 10/23/2015 12:00 AM
var startDate = new Date($('#schedule_start_date').val()).toISOString();
//Value displayed is 2015-10-23T04:00:00.000Z
alert('startDate: ' + startDate);
});
Why is the time value off by 4 hours?
Thanks
UPDATE
I need to add to the Date objects after they are created. Creating the Date object using the function in the answer below is not creating it in UTC format. It can be displayed in that format but when I am creating events in the fullcalendar control, the date must be in UTC format and they are not.
This is my function to create a schedule:
$("#rotation_schedule_btn").click(function () {
//create member list order
var memberList = [];
$("#rotationList li").each(function () {
memberList.push({
id: $(this).attr('id'),
name: $(this).text(),
color: $(this).css('background-color')
})
});
//start and end date and time for new schedule
var startDate = convertTextToDate($('#schedule_start_date').val())
var endDate = convertTextToDate($('#schedule_end_date').val());
//remove events between startDate & endDate
$('#edit_calendar').fullCalendar('removeEvents', function (event) {
if (event.start.toDate() >= startDate && event.start.toDate() <= endDate
|| event.end.toDate() >= startDate && event.end.toDate() <= endDate) {
return true;
}
});
//Create events from rotation schedule selected
var newEvents = [];
var rotation_length = $('#rotation_type_select option:selected').val();
var rotation_start_date = new Date(startDate.toISOString());
var rotation_end_date = new Date(startDate.toISOString());
//End date is to midnight
endDate.setMinutes(endDate.getMinutes() + 1);
rotation_end_date.setDate(rotation_end_date.getDate() + parseInt(rotation_length));
var member_index = 0;
while (rotation_end_date <= endDate)
{
// alert('start date: ' + rotation_start_date.toISOString() + ' end date: ' + rotation_end_date.toISOString());
var event = new Object();
event = {
title: memberList[member_index].name,
start: new Date (rotation_start_date.toISOString()),
end: new Date (rotation_end_date.toISOString()),
objectID: memberList[member_index].id,
color: memberList[member_index].color,
allDay: true,
textColor: 'white'
};
newEvents.push(event);
eventsAdded.push(event);
rotation_start_date.setDate(rotation_start_date.getDate() + parseInt(rotation_length));
rotation_end_date.setDate(rotation_end_date.getDate() + parseInt(rotation_length));
if ((memberList.length - 1) == member_index) {
member_index = 0;
}
else {
member_index++;
}
}
//Render events on calendar
$('#edit_calendar').fullCalendar('addEventSource', newEvents);
}); //end create schedule button click
The function to convert the dates is the same as below but I renamed the function:
function convertTextToDate(dateValue)
{
var dateArray = dateValue.split(/\D/);
var pm = /pm$/i.test(dateValue);
var hour = (+dateArray[3] || 0) % 12 + (pm ? 12 : 0);
var date = new Date(Date.UTC(dateArray[2], dateArray[0] - 1, dateArray[1], hour, +dateArray[4] || 0, +dateArray[5] || 0));
return date;
}
What am i doing wrong?

Date.prototype.toISOString() is based on a 0 offset UTC timezone. So it is trying to normalize your current timezone back to 0 UTC, because when you do new Date() you create a new date based on your current time zone, that is why the method is trying to revert your date back to UTC time zone. You are probably right now in a time zone which is 4h behind UTC.
http://devdocs.io/javascript/global_objects/date/toisostring
In order to fix this, just append your string with " UTC" and it will no longer do the timezone shifting:
10/23/2015 12:00 AM UTC
It will generate:
"2015-10-23T00:00:00.000Z"

Do not use the Date constructor to parse strings, particularly non-standard strings. Ever. Manually parse the string.
Since you have a fixed format, it's pretty straight forward to create a date based on UTC with the format in the OP
// Parse date format mm/dd/yyyy hh:mm:ss AP as UTC
function parseMDYA(s) {
var b = s.split(/\D/);
var pm = /pm$/i.test(s);
var h = (+b[3]||0)%12 + (pm? 12 : 0);
return new Date(Date.UTC(b[2], b[0]-1, b[1], h, +b[4]||0, +b[5]||0));
}
var s = '10/23/2015 12:00 AM';
var d = parseMDYA(s);
document.write('Input string: ' + s +
'<br>UTC time: ' + d.toISOString() +
'<br>Local time: ' + d
);
Time parts that aren't supplied are treated as 0.