Develop Reference

How can i get the first nearest date in the past?

I have this arrays
const datesToBeChecked = ['2020-07-03','2020-07-06', '2020-07-13', '2020-07-20']
const dateToCheckFor = '2020-07-12';
I need to get the first nearest date in the past - so when the date is 2020-07-12 i need to get
2020-07-06 from datesToBeChecked.
WHAT I TRIED
I tried this code
datesToBeChecked.forEach(date => {
let diff = moment(dateToCheckFor).diff(moment(date), 'days');
console.log(diff);
if (diff > 0) {
if (nearestDate) {
if (moment(date).diff(moment(nearestDate), 'days') < 0) {
nearestDate = date;
}
} else {
nearestDate = date;
}
}
});
but that gives me the earliest date in the array - 2020-07-03. But i need the first BEFORE THE DATE I CHECK FOR

Actually your logic is almost there. You don't need the nested if conditional. In essense, what you want is to cache the difference, and compare the current difference with the cached difference. If the cached difference is smaller, then we know the current date is the nearest one. Otherwise, we continue for the search.
This solution will work even if the dates are not sorted in chronological order (oldest to newest):
const datesToBeChecked = ['2020-07-03', '2020-07-06', '2020-07-13', '2020-07-20']
const dateToCheckFor = '2020-07-12';
let nearestDate;
let cachedDiff = Infinity;
datesToBeChecked.forEach(date => {
let diff = moment(dateToCheckFor).diff(moment(date), 'days');
if (diff > 0 && diff < cachedDiff) {
cachedDiff = diff;
nearestDate = date;
}
});
console.log(nearestDate);
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>

The first element is the closest date in the past (at least yesterday, today results won't show up).
If empty then dateToCheckFor elements does not contain any date in past.
const mappedDates = dateToCheckFor
.map(d => moment(dateToCheckFor).diff(moment(d), 'days'))
.filter(diff => diff <= -1)
.sort()
.reverse();

You could try sorting all of the dates in a hash table first. So you would have a hash table:
{
date1: difference,
date2: difference,
...
}
then you would sort the objects values, such as here: Sorting object property by values
then take the first date from that, which is before the dateToCheckFor
I hope this is not too inefficient for you.

Here's one way with good ole vanilla js. Moment.js weighs 230+kb
const datesToBeChecked = ['2020-07-03', '2020-07-06', '2020-07-13', '2020-07-20']
const dateToCheckFor = '2020-07-12';
dateToCheckFor_d = new Date(dateToCheckFor).getTime();
let possibilities = datesToBeChecked.filter(dt => {
return (new Date(dt).getTime() < dateToCheckFor_d)
})
possibilities.sort().reverse()
console.log(possibilities[0])

In your code just update the below line
if (moment(date).diff(moment(nearestDate), 'days') < 0
to
if (moment(date).diff(moment(nearestDate), 'days') > 0

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

Get days left till end of the month with moment.js

I want to display or hide a link depending on whether there are less than 2 weeks left in the month, using moment.js, but I'm not sure the correct way to go about it.
Currently I have...
if (moment().endOf('month')<=(13, 'days'))
{
//do link stuff here
}
...but I don't think that's the correct way of doing it. It certainly isn't doing anything anyway. Could anyone give me any pointers? Thanks in advance.

You could do something like this:
var a = moment().endOf('month');
var b = moment();
if(a.diff(b, 'days') <= 13)
{
//do something
}

If you're looking for a plain javascript version, I've wrote this function:
function getMonthDaysLeft(){
date = new Date();
return new Date(date.getFullYear(), date.getMonth() + 1, 0).getDate() - date.getDate();
}

Maybe something like this can help.
const d = moment();
const currentDay = d.get("date");
const daysInMonth = d.daysInMonth();
const remainingDays = daysInMonth - currentDay;
console.log(remainingDays <= 13)

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.

Date Parsing and Validation in JavaScript

How would I achieve the pseudo-code below in JavaScript? I want to include the date check in the second code excerpt, where txtDate is for the BilledDate.
If ABS(billeddate – getdate) > 31 then yesno “The date you have entered is more than a month from today, Are you sure the date is correct,”.
if (txtDate && txtDate.value == "")
{
txtDate.focus();
alert("Please enter a date in the 'Date' field.")
return false;
}

Generally speaking you work with Date-objects in javascript, and these should be constructed with the following syntax:
var myDate = new Date(yearno, monthno-1, dayno);
//you could put hour, minute, second and milliseconds in this too
Beware, the month-part is an index, so january is 0, february is 1 and december is 11 !-)
Then you can pull out anything you want, the .getTime() thing returns number of milliseconds since start of Unix-age, 1/1 1970 00:00, så this value you could subtract and then look if that value is greater than what you want:
//today (right now !-) can be constructed by an empty constructor
var today = new Date();
var olddate = new Date(2008,9,2);
var diff = today.getTime() - olddate.getTime();
var diffInDays = diff/(1000*60*60*24);//24 hours of 60 minutes of 60 second of 1000 milliseconds
alert(diffInDays);
This will return a decimal number, so probably you'll want to look at the integer-value:
alert(Math.floor(diffInDays));

To get the date difference in days in plain JavaScript, you can do it like this:
var billeddate = Date.parse("2008/10/27");
var getdate = Date.parse("2008/09/25");
var differenceInDays = (billeddate - getdate)/(1000*60*60*24)
However if you want to get more control in your date manipulation I suggest you to use a date library, I like DateJS, it's really good to parse and manipulate dates in many formats, and it's really syntactic sugar:
// What date is next thrusday?
Date.today().next().thursday();
//or
Date.parse('next thursday');
// Add 3 days to Today
Date.today().add(3).days();
// Is today Friday?
Date.today().is().friday();
// Number fun
(3).days().ago();

You can use this to check for valid date
function IsDate(testValue) {
var returnValue = false;
var testDate;
try {
testDate = new Date(testValue);
if (!isNaN(testDate)) {
returnValue = true;
}
else {
returnValue = false;
}
}
catch (e) {
returnValue = false;
}
return returnValue;
}
And this is how you can manipulate JS dates. You basically create a date object of now (getDate), add 31 days and compare it to the date entered
function IsMoreThan31Days(dateToTest) {
if(IsDate(futureDate)) {
var futureDateObj = new Date();
var enteredDateObj = new Date(dateToTest);
futureDateObj.setDate(futureDateObj.getDate() + 31); //sets to 31 days from now.
//adds hours and minutes to dateToTest so that the test for 31 days is more accurate.
enteredDateObj.setHours(futureDateObj.getHours());
enteredDateObj.setMinutes(futureDateObj.getMinutes() + 1);
if(enteredDateObj >= futureDateObj) {
return true;
}
else {
return false;
}
}
}

Hello and good day for everyone
You can try Refular Expressions to parse and validate a date format
here is an URL yoy can watch some samples and how to use
http://www.javascriptkit.com/jsref/regexp.shtml
A very very simple pattern would be: \d{2}/\d{2}/\d{4}
for MM/dd/yyyy or dd/MM/yyyy
With no more....
bye bye