Develop Reference

How would I fix this function to change month depending on the date?

I'm trying to create a function that creates a dynamic date range based on the date supplied in a string.
What I've done so far:
Capture date in the string I'm looking to change;
Check to see if that date is a Thursday (if so the range will need to account for the weekend)
What I need to do:
Find a way to get the second date in the range to account for the weekend;
Find a way to make sure that the second date takes into account the last day of the month.
Apologies for old syntax, GTM doesn't like anything using ES6 so I'm a little constrained on this project.
Note I am using DD/MM/YYYY
var regex = /[\d\/\d\/\d]/g;
var text = document.querySelector('.shipmentLineTitle b');
var originalDate = text.innerText.match(regex, "");
if (originalDate.length > 10) {
originalDate.pop();
originalDate.join('');
}
var ogDateString = originalDate.join('');
var dayNumber = originalDate.splice(0, 2).join('');
var monthNumber = originalDate.splice(1, 2).join('');
var yearNumber = originalDate.splice(2, 4).join('');
// if originalDate is a thursday (5) dynamicString will need to be a Monday (1).
var date = new Date(yearNumber, monthNumber -1, dayNumber);
var dynamicDateString = "";
if (date.getDay == 5) {
var newDate = new Date(date) + (86400000 * 3);
var dd = newDate.getDate();
var mm = newDate.getMonth() +1;
var yy = newDate.getFullYear();
dymamicDateString = dd + '/' + mm + '/' + yy;
} else {
var newDate = new Date(date) + 86400000;
var dd = newDate.getDate();
var mm = newDate.getMonth() +1;
var yy = newDate.getFullYear();
dynamicDateString = dd + '/' + mm + '/' + yy;
}
var newContent = 'Delivery will be made between ' + ogDateString + ' - ' + dynamicDateString + '. An accurate delivery date will be provided after you place your order.';
text.innerText = newContent;
<span class="shipmentLineTitle">Delivery details: <b>your delivery will arrive on 09/10/2020 (1 delivery)</b></span>

Thursday is day 4
Here is a simpler script
var textField = document.querySelector('.shipmentLineTitle b'),
text = textField.innerText,
originalDate = text.match(/\d{2}\/\d{2}\/\d{4}/)[0].split("/"),
dayNumber = +originalDate[0],
monthNumber = +originalDate[1],
yearNumber = +originalDate[2],
date = new Date(yearNumber, monthNumber - 1, dayNumber, 15, 0, 0, 0),
aDay = 86400000,
newDate = new Date(date),
day = date.getDay(),
daysToAdd = 1; // Sunday to Wednesday
// if originalDate is a Thursday (4) or Saturday (6), dynamicString will need to be a Monday (1).
if (day === 4) daysToAdd = 4; // Thursday - delivery Monday
else if (day === 6) daysToAdd = 2; // Saturday
newDate.setDate(newDate.getDate() + daysToAdd);
var dd = newDate.getDate(),
mm = newDate.getMonth() + 1,
yy = newDate.getFullYear(),
dynamicDateString = dd + '/' + mm + '/' + yy,
newContent = text + ' - ' + dynamicDateString + '</b>. An accurate delivery date will be provided after you place your order.';
textField.innerHTML = newContent;
<span class="shipmentLineTitle">Delivery details: <b>your delivery will arrive on 08/10/2020 (1 delivery)</b></span>

I would suggest to user moment.js a very good date library to manipulate dates. It has lot of function to add/substract dates, hours, days etc.
There is https://www.npmjs.com/package/moment-business-days which servers exactly what you need

Convert a timestamp to YYYY-MM-DD with JS [duplicate]

I am storing time in a MySQL database as a Unix timestamp and that gets sent to some JavaScript code. How would I get just the time out of it?
For example, in HH/MM/SS format.

let unix_timestamp = 1549312452
// Create a new JavaScript Date object based on the timestamp
// multiplied by 1000 so that the argument is in milliseconds, not seconds.
var date = new Date(unix_timestamp * 1000);
// Hours part from the timestamp
var hours = date.getHours();
// Minutes part from the timestamp
var minutes = "0" + date.getMinutes();
// Seconds part from the timestamp
var seconds = "0" + date.getSeconds();
// Will display time in 10:30:23 format
var formattedTime = hours + ':' + minutes.substr(-2) + ':' + seconds.substr(-2);
console.log(formattedTime);
For more information regarding the Date object, please refer to MDN or the ECMAScript 5 specification.

function timeConverter(UNIX_timestamp){
var a = new Date(UNIX_timestamp * 1000);
var months = ['Jan','Feb','Mar','Apr','May','Jun','Jul','Aug','Sep','Oct','Nov','Dec'];
var year = a.getFullYear();
var month = months[a.getMonth()];
var date = a.getDate();
var hour = a.getHours();
var min = a.getMinutes();
var sec = a.getSeconds();
var time = date + ' ' + month + ' ' + year + ' ' + hour + ':' + min + ':' + sec ;
return time;
}
console.log(timeConverter(0));

JavaScript works in milliseconds, so you'll first have to convert the UNIX timestamp from seconds to milliseconds.
var date = new Date(UNIX_Timestamp * 1000);
// Manipulate JavaScript Date object here...

Use:
var s = new Date(1504095567183).toLocaleDateString("en-US")
console.log(s)
// expected output "8/30/2017"
and for time:
var s = new Date(1504095567183).toLocaleTimeString("en-US")
console.log(s)
// expected output "3:19:27 PM"
see Date.prototype.toLocaleDateString()

Modern Solution (for 2020)
In the new world, we should be moving towards the standard Intl JavaScript object, that has a handy DateTimeFormat constructor with .format() method:
function format_time(s) {
const dtFormat = new Intl.DateTimeFormat('en-GB', {
timeStyle: 'medium',
timeZone: 'UTC'
});
return dtFormat.format(new Date(s * 1e3));
}
console.log( format_time(12345) ); // "03:25:45"
Eternal Solution
But to be 100% compatible with all legacy JavaScript engines, here is the shortest one-liner solution to format seconds as hh:mm:ss:
function format_time(s) {
return new Date(s * 1e3).toISOString().slice(-13, -5);
}
console.log( format_time(12345) ); // "03:25:45"
Method Date.prototype.toISOString() returns time in
simplified extended ISO 8601 format, which is always 24 or 27 characters long (i.e. YYYY-MM-DDTHH:mm:ss.sssZ or
±YYYYYY-MM-DDTHH:mm:ss.sssZ respectively). The timezone is always
zero UTC offset.
This solution does not require any third-party libraries and is supported in all browsers and JavaScript engines.

I'm partial to Jacob Wright's Date.format() library, which implements JavaScript date formatting in the style of PHP's date() function.
new Date(unix_timestamp * 1000).format('h:i:s')

I'd think about using a library like momentjs.com, that makes this really simple:
Based on a Unix timestamp:
var timestamp = moment.unix(1293683278);
console.log( timestamp.format("HH/mm/ss") );
Based on a MySQL date string:
var now = moment("2010-10-10 12:03:15");
console.log( now.format("HH/mm/ss") );

shortest one-liner solution to format seconds as hh:mm:ss: variant:
console.log(new Date(1549312452 * 1000).toISOString().slice(0, 19).replace('T', ' '));
// "2019-02-04 20:34:12"

In moment you must use unix timestamp:
const dateTimeString = moment.unix(1466760005).format("DD-MM-YYYY HH:mm:ss");

This works with PHP timestamps
var d = 1541415288860;
//var d =val.timestamp;
//NB: use + before variable name
var date = new Date(+d);
console.log(d);
console.log(date.toDateString());
console.log(date.getFullYear());
console.log(date.getMinutes());
console.log(date.getSeconds());
console.log(date.getHours());
console.log(date.toLocaleTimeString());
var d =val.timestamp;
var date=new Date(+d); //NB: use + before variable name
console.log(d);
console.log(date.toDateString());
console.log(date.getFullYear());
console.log(date.getMinutes());
console.log(date.getSeconds());
console.log(date.getHours());
console.log(date.toLocaleTimeString());
the methods above will generate this results
1541415288860
Mon Nov 05 2018
2018
54
48
13
1:54:48 PM
There's a bunch of methods that work perfectly with timestamps. Cant list them all

UNIX timestamp is number of seconds since 00:00:00 UTC on January 1, 1970 (according to Wikipedia).
Argument of Date object in Javascript is number of miliseconds since 00:00:00 UTC on January 1, 1970 (according to W3Schools Javascript documentation).
See code below for example:
function tm(unix_tm) {
var dt = new Date(unix_tm*1000);
document.writeln(dt.getHours() + '/' + dt.getMinutes() + '/' + dt.getSeconds() + ' -- ' + dt + '<br>');
}
tm(60);
tm(86400);
gives:
1/1/0 -- Thu Jan 01 1970 01:01:00 GMT+0100 (Central European Standard Time)
1/0/0 -- Fri Jan 02 1970 01:00:00 GMT+0100 (Central European Standard Time)

Using Moment.js, you can get time and date like this:
var dateTimeString = moment(1439198499).format("DD-MM-YYYY HH:mm:ss");
And you can get only time using this:
var timeString = moment(1439198499).format("HH:mm:ss");

The problem with the aforementioned solutions is, that if hour, minute or second, has only one digit (i.e. 0-9), the time would be wrong, e.g. it could be 2:3:9, but it should rather be 02:03:09.
According to this page it seems to be a better solution to use Date's "toLocaleTimeString" method.

Another way - from an ISO 8601 date.
var timestamp = 1293683278;
var date = new Date(timestamp * 1000);
var iso = date.toISOString().match(/(\d{2}:\d{2}:\d{2})/)
alert(iso[1]);

Based on #shomrat's answer, here is a snippet that automatically writes datetime like this (a bit similar to StackOverflow's date for answers: answered Nov 6 '16 at 11:51):
today, 11:23
or
yersterday, 11:23
or (if different but same year than today)
6 Nov, 11:23
or (if another year than today)
6 Nov 2016, 11:23
function timeConverter(t) {
var a = new Date(t * 1000);
var today = new Date();
var yesterday = new Date(Date.now() - 86400000);
var months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
var year = a.getFullYear();
var month = months[a.getMonth()];
var date = a.getDate();
var hour = a.getHours();
var min = a.getMinutes();
if (a.setHours(0,0,0,0) == today.setHours(0,0,0,0))
return 'today, ' + hour + ':' + min;
else if (a.setHours(0,0,0,0) == yesterday.setHours(0,0,0,0))
return 'yesterday, ' + hour + ':' + min;
else if (year == today.getFullYear())
return date + ' ' + month + ', ' + hour + ':' + min;
else
return date + ' ' + month + ' ' + year + ', ' + hour + ':' + min;
}

function getTIMESTAMP() {
var date = new Date();
var year = date.getFullYear();
var month = ("0" + (date.getMonth() + 1)).substr(-2);
var day = ("0" + date.getDate()).substr(-2);
var hour = ("0" + date.getHours()).substr(-2);
var minutes = ("0" + date.getMinutes()).substr(-2);
var seconds = ("0" + date.getSeconds()).substr(-2);
return year + "-" + month + "-" + day + " " + hour + ":" + minutes + ":" + seconds;
}
//2016-01-14 02:40:01

The modern solution that doesn't need a 40 KB library:
Intl.DateTimeFormat is the non-culturally imperialistic way to format a date/time.
// Setup once
var options = {
//weekday: 'long',
//month: 'short',
//year: 'numeric',
//day: 'numeric',
hour: 'numeric',
minute: 'numeric',
second: 'numeric'
},
intlDate = new Intl.DateTimeFormat( undefined, options );
// Reusable formatter
var timeStamp = 1412743273;
console.log( intlDate.format( new Date( 1000 * timeStamp ) ) );

Pay attention to the zero problem with some of the answers. For example, the timestamp 1439329773 would be mistakenly converted to 12/08/2015 0:49.
I would suggest on using the following to overcome this issue:
var timestamp = 1439329773; // replace your timestamp
var date = new Date(timestamp * 1000);
var formattedDate = ('0' + date.getDate()).slice(-2) + '/' + ('0' + (date.getMonth() + 1)).slice(-2) + '/' + date.getFullYear() + ' ' + ('0' + date.getHours()).slice(-2) + ':' + ('0' + date.getMinutes()).slice(-2);
console.log(formattedDate);
Now results in:
12/08/2015 00:49

There are multiple ways to convert unix timestamp to time (HH/MM/SS)
Using new Date() - this is in-built in javascript
moment package - this is a famous node module, but this is going to deprecate.
dayjs package - this is one of the latest and fast growing node module
Using new Date()
const dateTimeStr = new Date(1504052527183).toLocaleString()
const result = (dateTimeStr.split(", ")[1]).split(":").join("/")
console.log(result)
Using moment
const moment = require('moment')
const timestampObj = moment.unix(1504052527183);
const result = timestampObj.format("HH/mm/ss")
console.log(result);
Using day.js
const dayjs = require('dayjs')
const result = dayjs(1504052527183).format("HH/mm/ss")
console.log(result);
you can check the timestamp to time conversion with an online time conversion tool

// Format value as two digits 0 => 00, 1 => 01
function twoDigits(value) {
if(value < 10) {
return '0' + value;
}
return value;
}
var date = new Date(unix_timestamp*1000);
// display in format HH:MM:SS
var formattedTime = twoDigits(date.getHours())
+ ':' + twoDigits(date.getMinutes())
+ ':' + twoDigits(date.getSeconds());

function getDateTimeFromTimestamp(unixTimeStamp) {
let date = new Date(unixTimeStamp);
return ('0' + date.getDate()).slice(-2) + '/' + ('0' + (date.getMonth() + 1)).slice(-2) + '/' + date.getFullYear() + ' ' + ('0' + date.getHours()).slice(-2) + ':' + ('0' + date.getMinutes()).slice(-2);
}
const myTime = getDateTimeFromTimestamp(1435986900000);
console.log(myTime); // output 01/05/2000 11:00

You can use the following function to convert your timestamp to HH:MM:SS format :
var convertTime = function(timestamp, separator) {
var pad = function(input) {return input < 10 ? "0" + input : input;};
var date = timestamp ? new Date(timestamp * 1000) : new Date();
return [
pad(date.getHours()),
pad(date.getMinutes()),
pad(date.getSeconds())
].join(typeof separator !== 'undefined' ? separator : ':' );
}
Without passing a separator, it uses : as the (default) separator :
time = convertTime(1061351153); // --> OUTPUT = 05:45:53
If you want to use / as a separator, just pass it as the second parameter:
time = convertTime(920535115, '/'); // --> OUTPUT = 09/11/55
Demo
var convertTime = function(timestamp, separator) {
var pad = function(input) {return input < 10 ? "0" + input : input;};
var date = timestamp ? new Date(timestamp * 1000) : new Date();
return [
pad(date.getHours()),
pad(date.getMinutes()),
pad(date.getSeconds())
].join(typeof separator !== 'undefined' ? separator : ':' );
}
document.body.innerHTML = '<pre>' + JSON.stringify({
920535115 : convertTime(920535115, '/'),
1061351153 : convertTime(1061351153, ':'),
1435651350 : convertTime(1435651350, '-'),
1487938926 : convertTime(1487938926),
1555135551 : convertTime(1555135551, '.')
}, null, '\t') + '</pre>';
See also this Fiddle.

function timeConverter(UNIX_timestamp){
var a = new Date(UNIX_timestamp*1000);
var hour = a.getUTCHours();
var min = a.getUTCMinutes();
var sec = a.getUTCSeconds();
var time = hour+':'+min+':'+sec ;
return time;
}

See Date/Epoch Converter.
You need to ParseInt, otherwise it wouldn't work:
if (!window.a)
window.a = new Date();
var mEpoch = parseInt(UNIX_timestamp);
if (mEpoch < 10000000000)
mEpoch *= 1000;
------
a.setTime(mEpoch);
var year = a.getFullYear();
...
return time;

Shortest
(new Date(ts*1000)+'').slice(16,24)
let ts = 1549312452;
let time = (new Date(ts*1000)+'').slice(16,24);
console.log(time);

Try this :
new Date(1638525320* 1e3).toISOString() //2021-12-03T09:55:20.000Z

function getDateTime(unixTimeStamp) {
var d = new Date(unixTimeStamp);
var h = (d.getHours().toString().length == 1) ? ('0' + d.getHours()) : d.getHours();
var m = (d.getMinutes().toString().length == 1) ? ('0' + d.getMinutes()) : d.getMinutes();
var s = (d.getSeconds().toString().length == 1) ? ('0' + d.getSeconds()) : d.getSeconds();
var time = h + '/' + m + '/' + s;
return time;
}
var myTime = getDateTime(1435986900000);
console.log(myTime); // output 01/15/00

moment.js
convert timestamps to date string in js
https://momentjs.com/
moment().format('YYYY-MM-DD hh:mm:ss');
// "2020-01-10 11:55:43"
moment(1578478211000).format('YYYY-MM-DD hh:mm:ss');
// "2020-01-08 06:10:11"

If you want to convert Unix time duration to real hours, minutes, and seconds, you could use the following code:
var hours = Math.floor(timestamp / 60 / 60);
var minutes = Math.floor((timestamp - hours * 60 * 60) / 60);
var seconds = Math.floor(timestamp - hours * 60 * 60 - minutes * 60 );
var duration = hours + ':' + minutes + ':' + seconds;

Code below also provides 3-digit millisecs, ideal for console log prefixes:
const timeStrGet = date => {
const milliSecsStr = date.getMilliseconds().toString().padStart(3, '0') ;
return `${date.toLocaleTimeString('it-US')}.${milliSecsStr}`;
};
setInterval(() => console.log(timeStrGet(new Date())), 299);

How to alert current date in yyyy-mm-dd hrs:min:sec format in javascript?

In my program i need to alert current date with time in specific format(2015-11-18 12:23:00) so i am write like this
var date = new Date();
alert(date);
but the result is Wed Nov 18 2015 12:24:28 GMT+0530 (India Standard Time).
and also i am try like this
<script>
var d = new Date();
var c = new Date();
alert(formatDate(c));
alert(formatDate(d));
function formatDate(d)
{
var month = d.getMonth();
var day = d.getDate();
var hours = d.getHours();
var minutes = d.getMinutes();
month = month + 1;
month = month + "";
if (month.length == 1)
{
month = "0" + month;
}
day = day + "";
if (day.length == 1)
{
day = "0" + day;
}
hour = hour + "";
if (hour.length == 1)
{
hour = "0" + hour;
}
minute = minute + "";
if (minute.length == 1)
{
minute = "0" + minute;
}
return d.getFullYear()+month + '' + day + ''+ hour + '' + minute + '';
}</script>
it is also not working properly.
how can i do this in javascript and also i need to passed the veriable to database in another php file. please help me how can i do this

I think this below code are helpful us.
function getDateTimeFormate () {
now = new Date();
year = "" + now.getFullYear();
month = "" + (now.getMonth() + 1); if (month.length == 1) { month = "0" + month; }
day = "" + now.getDate(); if (day.length == 1) { day = "0" + day; }
hour = "" + now.getHours(); if (hour.length == 1) { hour = "0" + hour; }
minute = "" + now.getMinutes(); if (minute.length == 1) { minute = "0" + minute; }
second = "" + now.getSeconds(); if (second.length == 1) { second = "0" + second; }
return year + "-" + month + "-" + day + " " + hour + ":" + minute + ":" + second;
}
To get date time formate like.
alert(getDateTimeFormate());
// example alert message: 2011-05-18 15:20:12

Try this..
<script>
var currentdate = new Date();
var datetime = currentdate.getFullYear() + "-"
+ (currentdate.getMonth()+1) + "-"
+ currentdate.getDate() + " "
+ currentdate.getHours() + ":"
+ currentdate.getMinutes() + ":"
+ currentdate.getSeconds();
alert(datetime);
</script>
Output:2015-11-18 12:46:52
Demo:http://js.do/code/73749

Please try the following code:
Number.prototype.padLeft = function(base,chr){
var len = (String(base || 10).length - String(this).length)+1;
return len > 0? new Array(len).join(chr || '0')+this : this;
}
var d = new Date;
function formatDate(d){
dformat = [ (d.getMonth()+1).padLeft(),
d.getDate().padLeft(),
d.getFullYear()].join('-')+
' ' +
[ d.getHours().padLeft(),
d.getMinutes().padLeft(),
d.getSeconds().padLeft()].join(':');
return dformat;
}
alert(formatDate(d));
It will return : 11-18-2015 12:17:02. And to pass the value to a php code check this: How to pass JavaScript variables to PHP?

This might be useful
Date.prototype.yyyy = function() {
var yy = this.getFullYear().toString();
var mm = (this.getMonth()+1).toString();
var dd = this.getDate().toString();
var hh = this.getHours().toString();
var min = this.getMinutes().toString();
var ss = this.getSeconds().toString();
return yy +"-" +(mm[1]?mm:"0"+mm[0]) + "-" +(dd[1]?dd:"0"+dd[0])+" "+(hh[1]?hh:"0"+hh[0])+":"+(min[1]?min:"0"+min[0])+":"+(ss[1]?ss:"0"+ss[0]);
};
d = new Date();
d.yyyy();

From the below function you will get all the details you want to show use it according to your need
getMonth() - Returns a zero-based integer (0-11) representing the month of the year.
getDate() - Returns the day of the month (1-31).
getDay() - Returns the day of the week (0-6). 0 is Sunday, 6 is Saturday.
getHours() - Returns the hour of the day (0-23).
getMinutes() - Returns the minute (0-59).
getSeconds() - Returns the second (0-59).
getMilliseconds() - Returns the milliseconds (0-999).
getTimezoneOffset() - Returns the number of minutes between the machine local time and UTC.
var today = new Date();
var dd = today.getDate();
var mm = today.getMonth()+1; //January is 0!
var yyyy = today.getFullYear();
if(dd<10){
dd='0'+dd
}
if(mm<10){
mm='0'+mm
}
var today = dd+'/'+mm+'/'+yyyy;
document.getElementById("DATE").value = today;

Use this code:
var sec = d.getSeconds();
return d.getFullYear()+'-'+month + '-' + day + ' '+ hour + ':' + minute + ':'+sec;
instead of:
return d.getFullYear()+month + '' + day + ''+ hour + '' + minute + '';

Show current date

I am using the following to get the current date:-
var dateObj = new Date();
var month = dateObj.getUTCMonth() + 1;
var day = dateObj.getUTCDate();
var year = dateObj.getUTCFullYear();
var newdate = day + "/" + month + "/" + year;
If I alert(newdate); it shows:-
3/06/2013
Is there any way I can display this as:-
03/06/2013

With plain Javascript, only manually
if (day < 10) day = "0" + day;
if (month < 10) month = "0" + month;

If you want to avoid using a library, and don't mind an extra line in your JavaScript:
var day = dateObj.getUTCDate(),
dd = parseInt(day, 10) < 10 ? '0' + day : day;

Using JQuery DateFormat:
$.format.date(dateObj.toString(), "dd/MM/yyyy");

var mydate=new Date();
alert(mydate.toString('dd/MM/yyyy'));

function padWithZeroes(number, width)
{
while (number.length < width)
number = '0' + number;
return number;
}
Now call day = padWithZeroes(day, 2) (and likewise for the month) before you use it.

You can split it and create your own format:
var splitTime = newDate.split("/");
var day = splitTime[0];
var month = splitTime[1];
var year = splitTime[2];
if (day < 10){
day = "0" + day;
}
var myDate = day + '/' + month + '/' + year;
Living demo:
http://jsfiddle.net/rtqpp/

Please use the following:
var dateObj = new Date();
var month = ('0' + (dateObj.getUTCMonth() + 1) ).slice( -2 );;
var day = ('0' + (dateObj.getUTCDate() + 1) ).slice( -2 );
var year = dateObj.getUTCFullYear();
var newdate = day + "/" + month + "/" + year;

Combine date and time string into single date with javascript

I have a datepicker returning a date string, and a timepicker returning just a time string.
How should I combine those into a single javascript Date?
I thought I found a solution in Date.js. The examples shows an at( )-method, but I can't find it in the library...

You can configure your date picker to return format like YYYY-mm-dd (or any format that Date.parse supports) and you could build a string in timepicker like:
var dateStringFromDP = '2013-05-16';
$('#timepicker').timepicker().on('changeTime.timepicker', function(e) {
var timeString = e.time.hour + ':' + e.time.minute + ':00';
var dateObj = new Date(datestringFromDP + ' ' + timeString);
});
javascript Date object takes a string as the constructor param

Combine date and time to string like this:
1997-07-16T19:20:15
Then you can parse it like this:
Date.parse('1997-07-16T19:20:15');
You could also use moment.js or something similar.

For plain JavaScript:
combineDateAndTime = function(date, time) {
timeString = time.getHours() + ':' + time.getMinutes() + ':00';
var year = date.getFullYear();
var month = date.getMonth() + 1; // Jan is 0, dec is 11
var day = date.getDate();
var dateString = '' + year + '-' + month + '-' + day;
var combined = new Date(dateString + ' ' + timeString);
return combined;
};

You can concatenate the date and time, and then use moment to get the datetime
const date = '2018-12-24';
const time = '23:59:59';
const dateTime = moment(`${date} ${time}`, 'YYYY-MM-DD HH:mm:ss').format();

Boateng's example fails in cases where time consisted of hours, minutes, days or months that ranged from values 0-9 as getDate(), getMonth() etc... will return 1 digit in these cases and the time string will fail and an invalid date is returned:
function CombineDateAndTime(date, time) {
const mins = ("0"+ time.getMinutes()).slice(-2);
const hours = ("0"+ time.getHours()).slice(-2);
const timeString = hours + ":" + mins + ":00";
const year = date.getFullYear();
const month = ("0" + (date.getMonth() + 1)).slice(-2);
const day = ("0" + date.getDate()).slice(-2);
const dateString = "" + year + "-" + month + "-" + day;
const datec = dateString + "T" + timeString;
return new Date(datec);
};
Unfortunately do not have enough rep to comment

David's example with slight modifications:
function CombineDateAndTime(date, time) {
var timeString = time.getHours() + ':' + time.getMinutes() + ':00';
var ampm = time.getHours() >= 12 ? 'PM' : 'AM';
var year = date.getFullYear();
var month = date.getMonth() + 1; // Jan is 0, dec is 11
var day = date.getDate();
var dateString = '' + year + '-' + month + '-' + day;
var datec = dateString + 'T' + timeString;
var combined = new Date(datec);
return combined;
};

Concate date and time with moment JS which also works on firefox,
let d1 = moment().format('MM/DD/YYYY');
let dateTimeOpen = moment(d1 + ' ' + model.openingTime).format('YYYY-MM-DD HH:mm:ss');
let dateTimeClose = moment(d1 + ' ' + model.closingTime).format('YYYY-MM-DD HH:mm:ss');

const date = "2022-12-27";
const time = "16:26:42";
new Date(`${date}T${time});
output
Date Tue Dec 27 2022 16:26:42 GMT+0100 (Central European Standard Time)