Develop Reference

Date conversion resulting into time zone issue

I am trying to get functionality - if the user entered date is less than the current date I need to show an error message on the screen, I implemented the following code which is working fine in my local system date but not working in other time zones. Can anyone please help in getting this.
I need to use only javascript or jquery. I was not supposed to use other libraries.
dateFormat = function(value, event) {
let newValue = value.replace(/[^0-9]/g, '').replace(/(\..*)\./g, '$1');
const dayOrMonth = (index) => index % 2 === 1 && index < 4;
// on delete key.
if (!event.data) {
return value;
}
return newValue.split('').map((v, i) => dayOrMonth(i) ? v + '/' : v).join('');
}
checkStart = function(value) {
var newDate = new Date().toISOString();
var inputDate = new Date(value).toISOString();
var today = new Date(newDate).setHours(0,0,0,0);
var userDate = new Date(inputDate).setHours(0,0,0,0);
if(userDate < today) {
$('#error-msg3').show();
$('#startDate').val('');
} else {
$('#error-msg3').hide();
}
}
<input type="tel" maxlength="10" id="startDate" name="startDate" placeholder="mm/dd/yyyy"
oninput="this.value = dateFormat(this.value, event)" onblur="checkStart(this.value)" required/>
<span id="error">Start date should not be lesser than the current date.</span>
<script src="https://code.jquery.com/jquery-3.6.0.js"></script>

Server and Db May run on a different timezone, (UTC preferred ) and when you sen date as a string it doesn't have any timezone there instead it is just a string.
Try sending it as a timestamp or UTC date string
So that server and db will automatically convert it to their timzone and store it. and when any user fetch it from other time zone it will automatically converts to their timezone (but you store string it will just be treated as a string everywhere)
let d = new Date()
console.log(d.getTime())
//or get utc string
console.log(d.toUTCString())
Send this value to your server (API)

Your code runs entirely on the client so timezone is irrelevant.
In the OP there is:
var newDate = new Date().toISOString();
...
var today = new Date(newDate).setHours(0,0,0,0);
The conversion of Date to string to Date to number is inefficient and unnecessary. The following is equivalent:
let today = new Date().setHours(0,0,0,0);
Similarly for inputDate:
var inputDate = new Date(value).toISOString();
...
var userDate = new Date(inputDate).setHours(0,0,0,0);
is equivalent to:
let userDate = new Date(value).setHours(0,0,0,0);
All calculations are local so timezone is irrelevant. Also see Why does Date.parse give incorrect results?
Attempting to control user input using script is always fraught as there are many cases that are either impossible or impractical to code around. The use of a tel input for Dates is an example. The whole issue can be avoided by using a date input and setting a min value to today. Then users can't select a date before today and your issue is solved, e.g.
window.onload = function() {
let dateEl = document.getElementById('dateInput');
dateEl.min = new Date().toLocaleString('en-CA', {year:'numeric', month:'2-digit', day:'2-digit'});
}
<input id="dateInput" type="date">
If you are comparing the date sent by the user to a date on the server, then user system clock accuracy and timezone may be an issue, but that isn't explained in the OP.
If that is an issue, then you need to ask another question on that specific topic.
If you really want to manually control the input date and show an error message when invalid dates are selected, then parse the value from the date input and compare it to the start of today and go from there:
// Parse YYYY-MM-DD as local
function parseYMDLocal(s) {
let [Y, M, D] = s.split(/\D/);
return new Date(Y, M-1, D);
}
// Check if date in YYYY-MM-DD format is before today
function isBeforeToday(d) {
return parseYMDLocal(d) < new Date().setHours(0,0,0,0);
}
function checkValue() {
let errEl = document.getElementById('errEl');
errEl.textContent = '';
console.log(typeof this.value);
if (isBeforeToday(this.value)) {
errEl.textContent = 'Date must be today or later';
} else {
// do something else
}
}
window.onload = function() {
document.getElementById('dateInp').addEventListener('blur', checkValue, false);
}
#errEl {color: red}
<input id="dateInp" type="date"><span id="errEl"></span>

How to compare dates to make sure Google Apps Script is only sending an alert once a day?

I have a script in a Google Sheet that is sending out an alert if a certain condition is met. I want to trigger the script to run hourly, however, if an alert was already sent out today, I don't want to send out another one (only the next day). What is the best way to achieve this?
I've tried formatting the date several ways, but somehow the only thing working for me so far is getting the year, month and day from the date object as int and comparing them separately.
function sendAlert{
var now = new Date();
var yearNow = now.getYear();
var monthNow = now.getMonth() + 1;
var dayNow = now.getDate();
var sheet = SpreadsheetApp.getActive().getSheetByName('CHANGE_ALERT');
var sentYear = sheet.getRange("R2").getValue();
var sentMonth = sheet.getRange("S2").getValue();
var sentDay = sheet.getRange("T2").getValue();
if (yearNow != sentYear || monthNow != sentMonth || dayNow != sentDay) {
sendEmail();
var sentYear = sheet.getRange("R2").setValue(yearNow);
var sentMonth = sheet.getRange("S2").setValue(monthNow);
var sentDay = sheet.getRange("T2").setValue(dayNow);
else {
Logger.log('Alert was already sent today.');
}
}
I think this solution is definitely not the best approach, but I cannot come up with another that merges the date into one. Only comparing the new Date() doesn't work, since the time of day will not necessarily be the same. If I format the date to YYYY-MM-dd, it should work, but then when I get the date again from the spreadsheet it gets it as a full date with the time again.

Requirement:
Compare dates and send an email if one hasn't been sent already today.
Modified Code:
function sendAlert() {
var sheet = SpreadsheetApp.getActive().getSheetByName('blank');
var cell = sheet.getRange(2,18); //cell R2
var date = new Date();
var alertDate = Utilities.formatDate(cell.getValue(), "GMT+0", "yyyy-MM-dd");
var currentDate = Utilities.formatDate(date, "GMT+0", "yyyy-MM-dd");
if (alertDate !== currentDate) {
sendEmail();
cell.setValue(date);
} else {
Logger.log('Alert was already sent today.');
}
}
As you can see, I've removed all of your year/month/day code and replaced it with Utilities.formatDate(), this allows you to compare the dates in the format you specified in your question. I've also changed the if statement to match this, so now we only need to compare alertDate and currentDate.
References:
Utilities.formatDate()
Class SimpleDateFormat

Doing math towards future date

I am trying to figure out how to calculate future date compared to current date. For Example: (think of Deadline as a Date field)
- If Deadline (value form) is in the future but <= 12/31 of the current year, “This Year”
- If Deadline (value form) is in the future but > 12/31 of the current year, “Future”
So far, I am unable to figure this out within my code.
I need help with var theFuture AND to create a var for "is future but <= 21/31 of current year.
var theFuture = new Date("January 01 2020");
//theFuture.setDate(today.getDate());
//Compare the two numbers
if (dateToCheck < rightNow || dateToCheck == rightNow) {
theTiming = "Overdue";
g_form.setValue('u_timing', theTiming);
}
else if (dateToCheck >= approaching) {
theTiming = "Deadline Approaching";
g_form.setValue('u_timing', theTiming);
}
else if (dateToCheck > theFuture){
theTiming = "Future";
g_form.setValue('u_timing, theTiming');
}
}
So, results should be: When the user selects a date from Deadline, another field called Timing will generate Text. Current, I am able to calculate if the date selected is today or before today, Timing will say "Overdue". Next, if the date selected is greater than today BUT within 180 days, Timing will say "Deadline Approaching". But, to get the rest that I mentioned above, I am stuck.

We use moment.js for working with dates it makes things a lot easier.
This will tell you if the date selected is today or not:
var iscurrentDate = moment().isSame(dateToCheck, "day");
if(iscurrentDate)
{
}
You can also do a similar thing for year
var iscurrentDate = moment().isSame(dateToCheck, "year");
if(iscurrentDate)
{
}
More info on moment here: https://momentjs.com/docs/

Need explanation of this Date Processing function

Could anyone please explain the below code to me?
For example, i would like to set Today's date to today (21st of November, 2012) and the end date to the 3rd of December.
The reason for this is because i want to loop through a list of items, determine whether they are in the "past", "present" or "future" and assign a class to them accordingly.
I hope this makes sense! Any help is greatly appreciated and much welcomed!
function daysTilDate(expiredate){
expiredate ="12/"+expiredate+"/2012";
var thisDay=new Date(expiredate);
var CurrentDate = new Date();
var thisYear=CurrentDate.getFullYear();
thisDay.getFullYear(thisYear);
var DayCount=(thisDay-CurrentDate)/(1000*60*60*24);
DayCount=Math.round(DayCount);
return DayCount;
}

You can simplify the method like below if you want to calculate the days to an expire date. Please note that if you don't specify a test date, it'll take the current date as the test date.
​function ​daysTilData(expireDate, testDate) {
if(typeof testDate === "undefined"){
testDate = new Date(); // now
}
var diff = expireDate - testDate;
// minus value meaning expired days
return Math.round(diff/(1000*60*60*24));
}
alert(daysTilData(new Date("12/31/2012")));
// result 40
alert(daysTilData(new Date("12/31/2012"), new Date("1/12/2013")));
// result -12

Here's a line by line explanation.
The function declaration...
function daysTilDate(expiredate){
Takes the parameter expiredate sets it equal to the same value with "12/" prepended and "/2012" appended. so if the value of expiredate was "10", the new value is now "12/10/2012"...
expiredate ="12/"+expiredate+"/2012";
Instantiates a new Date object named thisDay using the expiredate string...
var thisDay=new Date(expiredate);
Instantiates a new Date object named CurrentDate, using the default constructor which will set the value equal to today's date...
var CurrentDate = new Date();
Gets just the Year segment from CurrentDate (which was earlier set to today's date)...
var thisYear=CurrentDate.getFullYear();
Gets the Year segment from thisDay (which was earlier set to "2012")...
thisDay.getFullYear(thisYear);
Gets the difference between thisDay and CurrentDate, which is in milliseconds, and multiplies that by 1000*60*60*24 to get the difference in days...
var DayCount=(thisDay-CurrentDate)/(1000*60*60*24);
Rounds the previously calculated difference...
DayCount=Math.round(DayCount);
Returns the difference between today and the passed-in day in December 2012...
return DayCount;
}
Note that the 2 lines that get the year segments are extraneous, because those values are never used...

I am not going to review the code, but I can answer your question of "I want to loop through a list of items, determine whether they are in the past, present, or future".
First, you want to construct your target date. If it's "now", just use new Date(). If it's a specific date, use new Date(dateString).
Second, Date objects in JavaScript have various members that return the date's characteristics. You can use this to compare dates. So, let's say you have your date strings in an array:
function loopDates(targetDateString, myDates) {
var targetDate, nextDate, status, ix;
targetDate = new Date(targetDateString);
for (ix = 0; ix < myDates.length; ++ix) {
nextDate = new Date(myDates[ix]);
if (nextDate.getFullYear() < targetDate.getFullYear()) {
status = "past";
} else if (nextDate.getFullYear() > targetDate.getFullYear()) {
status = "future";
} else {
// Year matches, compare month
if (nextDate.getMonth() < targetDate.getMonth()) {
status = "past";
} else if (nextDate.getMonth() > targetDate.getMonth()) {
status = "future";
} else {
// Month matches, compare day of month
if (nextDate.getDate() < targetDate.getDate()) {
status = "past";
} else if (nextDate.getDate() > targetDate.getDate()) {
status = "future";
} else {
// Day matches, present
status = "present";
}
}
}
console.log("Date " + myDates[ix] + " is " + status + " from " + targetDateString);
}
}
loopDates("11/17/2012", ["11/16/2012", "11/17/2012", "11/18/2012"]);
This will log:
Date 11/16/2012 is past from 11/17/2012
Date 11/17/2012 is present from 11/17/2012
Date 11/18/2012 is future from 11/17/2012
Working jsFiddle here.
If you want to work with a comprehensive Date class, use DateJS, an open source JavaScript date and time processing library with some impressive features.

JavaScript - Validate Date

I have an HTML text field. I want to validate via JavaScript that the value entered is a valid date in the form of "MM/DD/YY" or "MM/D/YY" or "MM/DD/YYYY" or "MM/D/YYYY". Is there a function that does this?
I sort of assumed there was something like isNaN but I don't see anything. Is it true that JavaScript can't validate dates?

You could use javascript's own Date object to check the date. Since the date object allows some mucking around with the month and day values (for example March 32 would be corrected to April 1), you can just check that the date you create matches the one you put in. You could shorten this if you want, but it's longer for clarity.
function checkDate(m,d,y)
{
try {
// create the date object with the values sent in (month is zero based)
var dt = new Date(y,m-1,d,0,0,0,0);
// get the month, day, and year from the object we just created
var mon = dt.getMonth() + 1;
var day = dt.getDate();
var yr = dt.getYear() + 1900;
// if they match then the date is valid
if ( mon == m && yr == y && day == d )
return true;
else
return false;
}
catch(e) {
return false;
}
}

Is it true that JavaScript can't validate dates?
No.
Is there a function that does this?
No.
You will need to write your own validation function to parse the date format (regex comes to mind) and then determine if it is valid within your specific criteria.

Check out http://momentjs.com/. Using it, this snippet
moment(yourCandidateString, 'MM-DD-YYYY').isValid()
should do the job.

This is what I use to validate a date.
Date.parse returns NaN for invalid dates.
This supports both date-only and date+time formats.
Hope this helps.
var msg;
var str = "2013-12-04 23:10:59";
str = "2012/12/42";
var resp = Date.parse(str);
if(!isNaN(resp)) { msg='valid date'; } else { msg='invalid date'; }
console.log(msg);

If you want to venture into the realms of JQuery there are plenty of validation plugins that include date validation. This plugin is one I've used a few times and has served me well.

I use Bootstrap Datepicker. One of the options with the text box disabled should do the trick.
http://www.eyecon.ro/bootstrap-datepicker/

<input type="text" id="dateinput"/>
<script type="text/javascript">
$(#"dateinput").datepicker({
buttonImage: "images/calendar.png",
dateFormat: "yyyy-MMM-dd"
});
function validateDate() {
if ($(#"dateinput").val().trim() == "") {
// Is a blank date allowed?
return true;
}
var oldVal = $(#"dateinput").val(); // Current value in textbox
// Now use jQueryUI datepicker to try and set the date with the current textbox value
$(#"dateinput").datepicker("setDate",$(#"dateinput").val());
// Check if the textbox value has changed
if (oldVal != $(#"dateinput").val()) {
// The datepicker will set something different if the date is invalid
$(#"dateinput").val(oldVal); // Set the textbox back to the invalid date
alert ("date was invalid");
return false;
} else {
// If nothing changed, the date must be good.
return true;
}
}
</script>

There does not appear to be a build-in function which does that. However, this code is probably what you're looking for:
<script type="text/javascript">
/**--------------------------
//* Validate Date Field script- By JavaScriptKit.com
//* For this script and 100s more, visit http://www.javascriptkit.com
//* This notice must stay intact for usage
---------------------------**/
function checkdate(input){
var validformat=/^\d{2}\/\d{2}\/\d{4}$/ //Basic check for format validity
var returnval=false
if (!validformat.test(input.value))
alert("Invalid Date Format. Please correct and submit again.")
else{ //Detailed check for valid date ranges
var monthfield=input.value.split("/")[0]
var dayfield=input.value.split("/")[1]
var yearfield=input.value.split("/")[2]
var dayobj = new Date(yearfield, monthfield-1, dayfield)
if ((dayobj.getMonth()+1!=monthfield)||(dayobj.getDate()!=dayfield)||(dayobj.getFullYear()!=yearfield))
alert("Invalid Day, Month, or Year range detected. Please correct and submit again.")
else
returnval=true
}
if (returnval==false) input.select()
return returnval
}
</script>
Source: http://www.javascriptkit.com/script/script2/validatedate.shtml

Have you googled for something like javascript date validation? It shows up some good information, and a working code example here.

I suggest you a couple of solutions.
guide the user input with a date picker. This way you can control the input format. jQueryui datepicker is a popular implementation.
use a js library to manage datetime data type (not an actual datatype in Javascript!!). I suggest you date.js.

Similar to this answer, Date can be used to check if the parsed version of the string corresponds to the original date string.
> datestring_valid = "2020-02-29";
> parsed_Date = new Date(datestring_valid);
> parsed_Date.toISOString().slice(0,10) == datestring_valid;
true
> datestring_invalid = "2021-02-29";
> parsed_Date = new Date(datestring_invalid);
> parsed_Date.toISOString().slice(0,10) == datestring_invalid;
false
NB: This requires the date string to be ISO formatted.
The reason this works is, that Date parses some invalid dates into something valid as in the example above. However, supplying "2020-01-32" into Date will result in the result being "Invalid Date" that isNaN.
A function that handles all of this is the following:
function isValidDateString(datestring) {
parsed_Date = new Date(datestring);
return (parsed_Date.toISOString().slice(0,10) == datestring) && !isNaN(parsed_Date)
};
> isValidDateString(datestring_valid)
true
> isValidDateString(datestring_invalid)
false