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How to find number of days from given days in js?

I need to find number of days if i enter startDate and endDate.from the start_date to end_date i only want to retrieve weekdays i.e monday to friday along with the offcial_leave variable
for_example:
let numberOfdays;
let startDate = '2022-04-04'; //yy-mm-dd format
let endDate = '2022-04-08';
// Below variable come from db and vary according the start and endate
// eg:- 2022-12-25 will be holiday if we select start and end in december
let holidays = ['2022-04-05', '2022-04-07' ]
numberOfdays => 3
// I want to return number of days to 3
How can i achieve this in in JavaScript
thanks

First convert the startDate and endDate to javascript Date. Then, declare a variable i to store while looping through the date. Also, declare holidayIndex which stores the current index at which holiday date needs to be checked with the current date.
Inside the loop, convert the date to YYYY-MM-DD format (original format) to check if the current date (isoDate) lies between a holiday, i.e., it is not a holiday date. If the holidayIndex is at last index of array, then just check if the current date (isoDate) is not in the holidays array. If not found, then increment numberOfDays variable.
Otherwise, a holiday date is found, hence no need to increment numberOfDays. Just increment holidayIndex to be ready to match the upcoming dates for next holiday date.
Here is the solution:
let numberOfdays = 0;
const startDate = '2022-04-04'; //yy-mm-dd format
const endDate = '2022-04-08';
// Below variable come from db and vary according the start and endate
// eg:- 2022-12-25 will be holiday if we select start and end in december
const holidays = ['2022-04-05', '2022-04-07'];
let holidayIndex = 0;
const start = new Date(startDate);
const end = new Date(endDate);
let i = start;
while (i <= end) {
const isoDate = i.toISOString().split('T')[0];
if (
(holidayIndex < holidays.length - 1 && isoDate < holidays[holidayIndex] && isoDate > holidays[holidayIndex + 1]) ||
formattedDate !== holidays[holidayIndex]
) {
numberOfdays += 1;
} else {
holidayIndex += 1;
}
i.setDate(i.getDate() + 1);
}

Display current week in react-native

I need to display the current week of the month in the following format in react-native:
(Week 2: 05.10 - 11.10) (example of week 2 of current month)
What would be some suggestions as how to achieve this? I know that there are packages such as momentjs to build this but would like some examples of how to achieve this
any help is appreciated!

You can adapt the code below. I say "adapt" because you haven't specified when your week starts (Sunday or Monday?) or how you want to count which week within the month it is (i.e. is week #1 the first full week? The code below assumes so).
Anyway, by clicking the "Run Code Snippet" button, you'll see what it does, including some intermediate steps, which are there to illustrate where the values are coming from, and therefore what you might want to "adapt" for your needs.
//get the first day of week and last day of week, borrowed from https://stackoverflow.com/a/64529257/1024832 above
const getWeek = (date = new Date()) => {
const dayIndex = date.getDay();
const diffToLastMonday = (dayIndex !== 0) ? dayIndex - 1 : 6;
const dateOfMonday = new Date(date.setDate(date.getDate() - diffToLastMonday));
const dateOfSunday = new Date(date.setDate(dateOfMonday.getDate() + 6));
return [dateOfMonday, dateOfSunday];
}
//get week number w/in the month, adapted from https://stackoverflow.com/a/57120367/1024832
const getWeekNumber = () => {
let todaysDate = moment(moment.now());
let endOfLastMonth = moment(todaysDate).startOf('month').subtract(1, 'week');
let weekOfMonth = todaysDate.diff(endOfLastMonth, 'weeks');
return weekOfMonth;
}
//capture/log some steps along the way
const [Monday, Sunday] = getWeek();
console.log("First/Last of week as Date Objects: ", Monday, Sunday);
let Monday_formatted = moment(Monday).format("DD.MM");
let Sunday_formatted = moment(Sunday).format("DD.MM");
console.log(Monday_formatted, "-", Sunday_formatted);
console.log("Week #:", getWeekNumber());
//set the DIV content
document.getElementById("datehere").innerText = `(Week ${getWeekNumber()}): ${Monday_formatted} - ${Sunday_formatted}`;
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.29.1/moment.min.js"></script>
<div id="datehere"></div>

Here's an answer as a function which returns the current week's Monday and Sunday in an array:
getWeek = (date = new Date()) => {
const dayIndex = date.getDay();
const diffToLastMonday = (dayIndex !== 0) ? dayIndex - 1 : 6;
const dateOfMonday = new Date(date.setDate(date.getDate() - diffToLastMonday));
const dateOfSunday = new Date(date.setDate(dateOfMonday.getDate() + 6));
return [dateOfMonday, dateOfSunday];
}
const [Monday, Sunday] = getWeek();
console.log(Monday, Sunday);
The response is two valid date objects. You can also pass a date object for the function to get Monday and Sunday of that date's week (e.g. getWeek(new Date(0));
But when you want to parse those dates, you should gain better knowledge of Date Object.

Javascript how to get full two year from current month?

I have question about getting full two years from the current date. So what i did id get the current month using the new date function and used the for loop to print each of the month. But, i cant really get it to work.... I will post the code that i did below. I would be really appreciate it if anyone can tell me the logic or better way of doing it.
For example: if today current date is august it store into an array from 8 / 2020 9/ 2020 ..... 12/ 2020, 1/2021 and goes to another year to 8/2022.
var d = new Date();
var year = d.getFullYear();
var dateStr;
var currentYear;
var storeMonthYear = [];
for(var i = 1; i <= 24; i++){
dateStr = d.getMonth() + i
currentYear = year;
if(dateStr > "12"){
dateStr = dateStr - 12
// currentYear = year;
// if(currentYear){
// }
storeMonthYear[i] = dateStr + "/" + (currentYear + 1);
}
else if(dateStr > "24"){
storeMonthYear[i] = dateStr + "/" + (currentYear + 1);
}
else{
storeMonthYear[i] = dateStr + "/" + currentYear;
}
storeMonthYear[i] = d.getMonth() + i
}
export const settlementPeriod = [
{
MonthYearFirstRow1: storeMonthYear[1],
MonthYearFirstRow2: storeMonthYear[2],
MonthYearFirstRow3: storeMonthYear[3],
MonthYearFirstRow4: storeMonthYear[4],
MonthYearFirstRow5: storeMonthYear[5],
MonthYearFirstRow6: storeMonthYear[6],
MonthYearFirstRow7: storeMonthYear[7],
MonthYearFirstRow8: storeMonthYear[8],
MonthYearFirstRow9: storeMonthYear[9],
MonthYearFirstRow10: storeMonthYear[10],
MonthYearFirstRow11: storeMonthYear[11],
MonthYearFirstRow12: storeMonthYear[12],
MonthYearSecondRow13: storeMonthYear[13],
MonthYearSecondRow14: storeMonthYear[14],
MonthYearSecondRow15: storeMonthYear[15],
MonthYearSecondRow16: storeMonthYear[16],
MonthYearSecondRow17: storeMonthYear[17],
MonthYearSecondRow18: storeMonthYear[18],
MonthYearSecondRow19: storeMonthYear[19],
MonthYearSecondRow20: storeMonthYear[20],
MonthYearSecondRow21: storeMonthYear[21],
MonthYearSecondRow22: storeMonthYear[22],
MonthYearSecondRow23: storeMonthYear[23],
MonthYearSecondRow24: storeMonthYear[24]
},
];

Create the date from today, get the month and year. Iterate from 0 to 24 for now till in 24 months. If month is 12 than set month to 0 and increment the year. Push the new datestring. Increment the month for the next step.
Note: Beacsue JS counts months form 0-11 you had to add for the datestring 1 for the month and make the change of year at 12 and not 13.
let date = new Date();
let year = date.getFullYear();
let month = date.getMonth();
let res=[];
for (let i=0; i<=24; i++) {
if (month===12) {
month = 0;
year++;
}
res.push(month+1 + '/' + year);
month++;
}
console.log(res);

Here you go, you get an array of strings like "8/2020","9/2020" etc from starting month to the last month including both( in total 25 months).
If you don't want to include last month just delete +1 from for loop condition.
let currentDate = new Date();
let settlementPeriod = [];
let numberOfMonths = 24;
for(let i=0;i<numberOfMonths+1;i++){
settlementPeriod.push(currentDate.getMonth()+1+"/"+currentDate.getFullYear()); //We add current date objects attributes to the array
currentDate = new Date(currentDate.setMonth(currentDate.getMonth()+1)); //Every time we add one month to it
}
console.log(settlementPeriod);

There are a couple of things that stick out in your code sample:
You're comparing strings and numbers (e.g. dateStr > "12"). This will lead to some weird bugs and is one of JS's most easily misused "features". Avoid it where possible.
You increment the year when you reach 12 months from now, rather than when you reach the next January
You're overwriting your strings with this line storeMonthYear[i] = d.getMonth() + i so your array is a bunch of numbers rather than date strings like you expect
Here's a code sample that I think does what you're expecting:
function next24Months() {
const today = new Date()
let year = today.getFullYear()
let monthIndex = today.getMonth()
let dates = []
while (dates.length < 24) {
dates.push(`${monthIndex + 1}/${year}`)
// increment the month, and if we're past December,
// we need to set the year forward and the month back
// to January
if (++monthIndex > 11) {
monthIndex = 0
year++
}
}
return dates
}
In general, when you're dealing with dates, you're probably better off using a library like Moment.js - dates/times are one of the most difficult programming concepts.

While #Ognjen 's answer is correct it's also a bit waseful if your date never escapes its function.
You don't need a new date every time:
function getPeriods(firstMonth, numPers){
var d = new Date(firstMonth.getTime()); // clone the start to leave firstMonth alone
d.setDate(1); // fix after #RobG
var pers = [];
var m;
for(var i = 0; i< numPers; i++){
m = d.getMonth();
pers.push(`${m+ 1}/${d.getFullYear()}`)
d.setMonth(m + 1); // JS dates automatically roll over. You can do this with d.setDate() as well and when you assign 28, 29, 31 or 32 the month and year roll over automatically
}
return pers;
}

Determine if the date is today or is in the past using MomentJS?

Im building a mini calendar that just displays the current month, I have figured out how to map out the calendar, here is the code:
Code:
var month = moment(),
index = 0,
maxDay = month.daysInMonth(),
start = month.startOf("month"),
offset = (start.isoWeekday() - 1 + 7) % 7; // start from monday
var week = []; // holds the weeks
var days = []; // holds the days
do {
var dayIndex = index - offset;
if(dayIndex >= 0 && dayIndex < maxDay){
days.push({
number: dayIndex + 1,
isPast: null, // stuck here boolean
isToday: null // stuck here boolean
})
}
if(index % 7 === 6){
week.push(days);
console.log(week);
days = [];
if (dayIndex + 1 >= maxDay) {
break;
}
}
index += 1;
} while(true);
This works fine, the only issue Im having is to figure out if the day is today or its in the past?
the code is here also: https://jsfiddle.net/chghb3Lq/3/

Moment has isBefore, isAfter and isSame functions to compare moments and as the docs says:
If you want to limit the granularity to a unit other than milliseconds, pass the units as the second parameter.
There are a couple of things in your code that you can achieve in a simple way using momentjs instead of reimplementing by yourself:
To loop from the first day of the month until the last day you can use:
startOf('month') and endOf('month') as limit of the loop
add(1, 'day') to increment loop index
isBefore as loop condition
Use date() to get date of the month (1-31)
Use day() to get day of the week (0 => Sunday, ... 6 => Saturday); or weekday() to get day of the week locale aware.
Using these suggestions your code could be like the following:
var day = moment().startOf('month');
var endOfMonth = moment().endOf('month');
var week = [];
var month = [];
while( day.isBefore(endOfMonth) ){
week.push({
number: day.date(),
isPast: moment().isAfter(day, 'day'),
isToday: moment().isSame(day, 'day')
});
if( day.day() === 0 ){
month.push(week);
week = [];
}
day.add(1, 'day');
}
console.log(month);
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>

Use moment methods like isSame() , isBefore(), isSameOrBefore() etc.
They each allow setting comparison units like year month week day hour minute second
See Query Section of moment docs

How to compare dates in Javascript without using year?

The title says it all. I'm using MomentJS in other areas, so I am comfortable with a solution that uses moment (or not - either way is fine). In this solution, the function would return the shortest path to the compared date. e.g. comparing 12-31 to 01-01 would return 1, not 364. Basically this is what I am looking to do:
var today = '08-06'; // august 6th
var dateOne = '09-03' // september 3rd
var dateTwo = '02-29' // february 29th
var dateThree = '01-01' // january 1st
getDifferenceInDays(today, dateOne); // => 28
getDifferenceInDays(today, dateTwo); // => -159
getDifferenceInDays(today, dateThree); // => 147

This works with MomentJS. The caveat is that when you initialize MomentJS date it implicitly adds the year to this year. So, the assumption is that these values are calculated for this year
function getDifferenceInDays(date1, date2) {
var day1 = moment(date1,'MM-DD').dayOfYear();
var day2 = moment(date2,'MM-DD').dayOfYear();
var diff1=(day2 - day1)
var diff2=365- Math.abs(diff1)
if (Math.abs(diff1)>Math.abs(diff2)) {
return diff2;
} else {
return diff1;
}
}
var today = '08-06'; // august 6th
var dateOne = '09-03' // september 3rd
var dateTwo = '02-29' // february 29th
var dateThree = '01-01' // january 1st
console.log(";;;;")
console.log(getDifferenceInDays(today, dateOne)); // => 28
console.log(getDifferenceInDays(today, dateTwo)); // => -159
console.log(getDifferenceInDays(today, dateThree)); // => 147
http://jsfiddle.net/r2brgf4r/

You should be able to do this pretty easily with MomentJS by getting the month and day of the month from your Date object.
var getDifferenceInDays = function(date1, date2) {
var day1 = date1.dayOfYear();
var day2 = date2.dayOfYear();
if (Math.abs(day1 - day2) < (365 - Math.abs(day2 - day1))) {
return Math.abs(day1 - day2);
} else {
return (365 - Math.abs(day1 - day2));
}
}
Moment's "dayOfYear()" function returns the day of the year (a number between 1 and 366). Hope this helps!