How to validate a date? - javascript

I'm trying to test to make sure a date is valid in the sense that if someone enters 2/30/2011 then it should be wrong.
How can I do this with any date?

One simple way to validate a date string is to convert to a date object and test that, e.g.
// Expect input as d/m/y
function isValidDate(s) {
var bits = s.split('/');
var d = new Date(bits[2], bits[1] - 1, bits[0]);
return d && (d.getMonth() + 1) == bits[1];
}
['0/10/2017','29/2/2016','01/02'].forEach(function(s) {
console.log(s + ' : ' + isValidDate(s))
})
When testing a Date this way, only the month needs to be tested since if the date is out of range, the month will change. Same if the month is out of range. Any year is valid.
You can also test the bits of the date string:
function isValidDate2(s) {
var bits = s.split('/');
var y = bits[2],
m = bits[1],
d = bits[0];
// Assume not leap year by default (note zero index for Jan)
var daysInMonth = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
// If evenly divisible by 4 and not evenly divisible by 100,
// or is evenly divisible by 400, then a leap year
if ((!(y % 4) && y % 100) || !(y % 400)) {
daysInMonth[1] = 29;
}
return !(/\D/.test(String(d))) && d > 0 && d <= daysInMonth[--m]
}
['0/10/2017','29/2/2016','01/02'].forEach(function(s) {
console.log(s + ' : ' + isValidDate2(s))
})

Does first function isValidDate(s) proposed by RobG will work for input string '1/2/'?
I think NOT, because the YEAR is not validated ;(
My proposition is to use improved version of this function:
//input in ISO format: yyyy-MM-dd
function DatePicker_IsValidDate(input) {
var bits = input.split('-');
var d = new Date(bits[0], bits[1] - 1, bits[2]);
return d.getFullYear() == bits[0] && (d.getMonth() + 1) == bits[1] && d.getDate() == Number(bits[2]);
}

I recommend to use moment.js. Only providing date to moment will validate it, no need to pass the dateFormat.
var date = moment("2016-10-19");
And then date.isValid() gives desired result.
Se post HERE

This solution does not address obvious date validations such as making sure date parts are integers or that date parts comply with obvious validation checks such as the day being greater than 0 and less than 32. This solution assumes that you already have all three date parts (year, month, day) and that each already passes obvious validations. Given these assumptions this method should work for simply checking if the date exists.
For example February 29, 2009 is not a real date but February 29, 2008 is. When you create a new Date object such as February 29, 2009 look what happens (Remember that months start at zero in JavaScript):
console.log(new Date(2009, 1, 29));
The above line outputs: Sun Mar 01 2009 00:00:00 GMT-0800 (PST)
Notice how the date simply gets rolled to the first day of the next month. Assuming you have the other, obvious validations in place, this information can be used to determine if a date is real with the following function (This function allows for non-zero based months for a more convenient input):
var isActualDate = function (month, day, year) {
var tempDate = new Date(year, --month, day);
return month === tempDate.getMonth();
};
This isn't a complete solution and doesn't take i18n into account but it could be made more robust.

var isDate_ = function(input) {
var status = false;
if (!input || input.length <= 0) {
status = false;
} else {
var result = new Date(input);
if (result == 'Invalid Date') {
status = false;
} else {
status = true;
}
}
return status;
}
this function returns bool value of whether the input given is a valid date or not. ex:
if(isDate_(var_date)) {
// statements if the date is valid
} else {
// statements if not valid
}

I just do a remake of RobG solution
var daysInMonth = [31,28,31,30,31,30,31,31,30,31,30,31];
var isLeap = new Date(theYear,1,29).getDate() == 29;
if (isLeap) {
daysInMonth[1] = 29;
}
return theDay <= daysInMonth[--theMonth]

This is ES6 (with let declaration).
function checkExistingDate(year, month, day){ // year, month and day should be numbers
// months are intended from 1 to 12
let months31 = [1,3,5,7,8,10,12]; // months with 31 days
let months30 = [4,6,9,11]; // months with 30 days
let months28 = [2]; // the only month with 28 days (29 if year isLeap)
let isLeap = ((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0);
let valid = (months31.indexOf(month)!==-1 && day <= 31) || (months30.indexOf(month)!==-1 && day <= 30) || (months28.indexOf(month)!==-1 && day <= 28) || (months28.indexOf(month)!==-1 && day <= 29 && isLeap);
return valid; // it returns true or false
}
In this case I've intended months from 1 to 12. If you prefer or use the 0-11 based model, you can just change the arrays with:
let months31 = [0,2,4,6,7,9,11];
let months30 = [3,5,8,10];
let months28 = [1];
If your date is in form dd/mm/yyyy than you can take off day, month and year function parameters, and do this to retrieve them:
let arrayWithDayMonthYear = myDateInString.split('/');
let year = parseInt(arrayWithDayMonthYear[2]);
let month = parseInt(arrayWithDayMonthYear[1]);
let day = parseInt(arrayWithDayMonthYear[0]);

My function returns true if is a valid date otherwise returns false :D
function isDate (day, month, year){
if(day == 0 ){
return false;
}
switch(month){
case 1: case 3: case 5: case 7: case 8: case 10: case 12:
if(day > 31)
return false;
return true;
case 2:
if (year % 4 == 0)
if(day > 29){
return false;
}
else{
return true;
}
if(day > 28){
return false;
}
return true;
case 4: case 6: case 9: case 11:
if(day > 30){
return false;
}
return true;
default:
return false;
}
}
console.log(isDate(30, 5, 2017));
console.log(isDate(29, 2, 2016));
console.log(isDate(29, 2, 2015));

It's unfortunate that it seems JavaScript has no simple way to validate a date string to these days. This is the simplest way I can think of to parse dates in the format "m/d/yyyy" in modern browsers (that's why it doesn't specify the radix to parseInt, since it should be 10 since ES5):
const dateValidationRegex = /^\d{1,2}\/\d{1,2}\/\d{4}$/;
function isValidDate(strDate) {
if (!dateValidationRegex.test(strDate)) return false;
const [m, d, y] = strDate.split('/').map(n => parseInt(n));
return m === new Date(y, m - 1, d).getMonth() + 1;
}
['10/30/2000abc', '10/30/2000', '1/1/1900', '02/30/2000', '1/1/1/4'].forEach(d => {
console.log(d, isValidDate(d));
});

Hi Please find the answer below.this is done by validating the date newly created
var year=2019;
var month=2;
var date=31;
var d = new Date(year, month - 1, date);
if (d.getFullYear() != year
|| d.getMonth() != (month - 1)
|| d.getDate() != date) {
alert("invalid date");
return false;
}

function isValidDate(year, month, day) {
var d = new Date(year, month - 1, day, 0, 0, 0, 0);
return (!isNaN(d) && (d.getDate() == day && d.getMonth() + 1 == month && d.getYear() == year));
}

Related

How to calculate new date after date validation?

I'm using Elian Ebbing's data validation code from here and after validation, I'd like to take the date entered and return a new date for X amount of months later. For example, if I entered 06/09/2019, I would then like the code to return the correct new date that's 6 months later, which would be 12/6/2019.
Can someone please help guide me through the process of accomplishing this? I have been trying different methods of reusing the original code to get the results that I want, however I have been at this since July 2nd and have concluded I just can't figure this out on my own. I am completely stumped.
Lastly, my deepest apologies in advance that I didn't just comment on the original thread for Mr. Ebbing's code and ask for help, but unfortunately I did not have enough reputation points to do so.
If you are not sure that it is good to use some library (moment.js). If you want to find something already discovered, be ready to bump your head.
// Elian Ebbing validator
function isValidDate(dateString) {
// First check for the pattern
if(!/^\d{1,2}\/\d{1,2}\/\d{4}$/.test(dateString))
return false;
// Parse the date parts to integers
var parts = dateString.split("/");
var day = parseInt(parts[1], 10);
var month = parseInt(parts[0], 10);
var year = parseInt(parts[2], 10);
// Check the ranges of month and year
if(year < 1000 || year > 3000 || month == 0 || month > 12)
return false;
var monthLength = [ 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 ];
// Adjust for leap years
if(year % 400 == 0 || (year % 100 != 0 && year % 4 == 0))
monthLength[1] = 29;
// Check the range of the day
return day > 0 && day <= monthLength[month - 1];
}
// if you want to change date format
function formatDate(date) {
var d = new Date(date),
month = '' + (d.getMonth() + 1), // monts start form 0 so for result 06/01/2019
day = '' + d.getDate(),
year = d.getFullYear();
if (month.length < 2) {
month = '0' + month;
}
if (day.length < 2) {
day = '0' + day;
}
return [month, day, year].join('/');
}
// increment Date with count of months
function incrementDate(date, counter = 0) {
if (isValidDate(start_date_value)) {
var newDate = new Date(date);
newDate.setMonth(newDate.getMonth() + counter);
console.log(formatDate(newDate));
}
}
var start_date_value = "01/01/2019";
incrementDate(start_date_value, 5) ; // 06/01/2019

How to get a specify date in every month in Javascript?

I need to find this month, previous month and the next month of a specific date.
For example, date was set to 31 of every month, what I expect to get the date is
2018-02-28, 2018-03-31 and 2018-04-30. For those dates which has no 31, than it becomes the day before.
And finally generate 2 period, 2018-02-28 to 2018-03-29, 2018-03-30 to 2018-04-31.
I don't know how to handle feb and the month which less than 31.
var d = new Date();
var tyear = d.getFullYear(); //2018
var tmonth = d.getMonth(); //2
new Date(2018, tmonth-1, 31);//output 2018-03-02 not what I wanted
A simple algorithm is to add months to the original date, and if the new date is wrong, set it to the last day of the previous month. Keeping the original date values unmodified helps, e.g.
/* #param {Date} start - date to start
** #param {number} count - number of months to generate dates for
** #returns {Array} monthly Dates from start for count months
*/
function getMonthlyDates(start, count) {
var result = [];
var temp;
var year = start.getFullYear();
var month = start.getMonth();
var startDay = start.getDate();
for (var i=0; i<count; i++) {
temp = new Date(year, month + i, startDay);
if (temp.getDate() != startDay) temp.setDate(0);
result.push(temp);
}
return result;
}
// Start on 31 Jan in leap year
getMonthlyDates(new Date(2016,0,31), 4).forEach(d => console.log(d.toString()));
// Start on 31 Jan not in leap year
getMonthlyDates(new Date(2018,0,31), 4).forEach(d => console.log(d.toString()));
// Start on 30 Jan
getMonthlyDates(new Date(2018,0,30), 4).forEach(d => console.log(d.toString()));
// Start on 5 Jan
getMonthlyDates(new Date(2018,0,5), 4).forEach(d => console.log(d.toString()));
I think you're going to need an array with 12 numbers in it. Each number is the amount of days in each month and the numbers in the array go in order (first number is 31 because January has 31 days, second is 28 or 29 for Feb), etc. Then you'll get the month number from your input date and look in the array at the number corresponding to the month number +/- 1.
You'll then need to construct a date for the previous month and the next month based on the number of days in the current month.
See comments inline:
let daysInMonths = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
document.getElementById("date").addEventListener("input", function(){
console.clear();
// Create new Date based on value in date picker
var selectedDate = new Date(this.value + 'T00:00');
var year = selectedDate.getYear();
// Determine if it is a leap year (Feb has 29 days) and update array if so.
if (((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0)) {
daysInMonths[1] = 29;
}
var selectedDateMonth = selectedDate.getMonth();
// Get previous month number (if current month is January, get December)
let prevMonth = selectedDateMonth > 0 ? selectedDateMonth - 1 : 11;
let prevMonthDate = null;
// If selected date is last day of month...
if(selectedDate.getDate() === daysInMonths[selectedDateMonth]){
// Create new date that takes the selected date and subtracts the correct amount of
// days from it based on a lookup in the array.
var newDate1 = new Date(selectedDate.getTime());
prevMonthDate =
new Date(newDate1.setDate(selectedDate.getDate() - daysInMonths[selectedDateMonth]));
} else {
// Create a new date that is last month and one day earlier
var newDate2 = new Date(selectedDate.getTime());
prevMonthDate =
new Date(new Date(newDate2.setDate(selectedDate.getDate() - 1))
.setMonth(selectedDate.getMonth() - 1));
}
// Get next month (if current month is December, get January
let nextMonth = selectedDateMonth < 11 ? selectedDateMonth + 1 : 0;
let nextMonthDate = null;
// Same idea for next month, but add instead of subtract.
// If selected date is last day of month...
if(selectedDate.getDate() === daysInMonths[selectedDateMonth]){
var newDate3 = new Date(selectedDate.getTime());
nextMonthDate =
new Date(newDate3.setDate(selectedDate.getDate() + daysInMonths[selectedDateMonth + 1]));
} else {
var newDate4 = new Date(selectedDate.getTime());
nextMonthDate = new Date(new Date(newDate4.setDate(selectedDate.getDate() + 1)).setMonth(selectedDate.getMonth() + 1));
}
console.log("Last month date: " + prevMonthDate.toLocaleDateString());
console.log("Next month date: " + nextMonthDate.toLocaleDateString());
});
<p>Pick a date: <input type="date" id="date"></p>
Use this approach:
Javascript Date Object – Adding and Subtracting Months
From the Author
There is a slight problem with the Javascript Date() Object when trying to advance to the next month or go back to the previous month.
For example, if your date is set to October 31, 2018 and you add one month, you'd probably expect the new date to be November 30, 2018 because November 31st doesn't exist. This, however, isn't the case.
Javascript automatically advances your Date object to December 1st. This functionality is very useful in most situations(i.e. adding days to a date, determining the number of days in a month or if it's a leap year), but not for adding/subtracting months. I've put together some functions below that extend the Date() object: nextMonth() and prevMonth().
function prevMonth() {
var thisMonth = this.getMonth();
this.setMonth(thisMonth - 1);
if (this.getMonth() != thisMonth - 1 && (this.getMonth() != 11 || (thisMonth == 11 && this.getDate() == 1)))
this.setDate(0);
}
function nextMonth() {
var thisMonth = this.getMonth();
this.setMonth(thisMonth + 1);
if (this.getMonth() != thisMonth + 1 && this.getMonth() != 0)
this.setDate(0);
}
Date.prototype.nextMonth = nextMonth;
Date.prototype.prevMonth = prevMonth;
var today = new Date(2018, 2, 31); //<----- March 31st, 2018
var prevMonth = new Date(today.getTime());
prevMonth.prevMonth();
console.log("Previous month:", prevMonth);
console.log("This month:", today)
var nextMonth = new Date(today.getTime());
nextMonth.nextMonth();
console.log("Next month:", nextMonth);
.as-console-wrapper { max-height: 100% !important; top: 0; }
Dates and time zones are a real pain in JS, so challenge accepted.
I broke it down in two steps:
- Count the days of prev and next month
- Compare with selected day and pick the lowest number
Testcases included
function createUTCDate(year, month, day) {
return new Date(Date.UTC(year, month, day));
}
function splitDate(date) {
return {
year: date.getUTCFullYear(),
month: date.getUTCMonth(),
day: date.getUTCDate()
};
}
function numberOfDaysInMonth(year, month) {
return new Date(year, month + 1, 0).getDate();
}
function dateNextMonth(dateObj) {
const daysNextMonth = numberOfDaysInMonth(dateObj.year, dateObj.month + 1);
const day = Math.min(daysNextMonth, dateObj.day);
return createUTCDate(dateObj.year, dateObj.month + 1, day);
}
function datePreviousMonth(dateObj) {
const daysPrevMonth = numberOfDaysInMonth(dateObj.year, dateObj.month - 1);
const day = Math.min(daysPrevMonth, dateObj.day);
return createUTCDate(dateObj.year, dateObj.month - 1, day);
}
const log = console.log;
function print(dateString) {
const date = new Date(dateString);
const dateObj = splitDate(date);
log("Previous: ", datePreviousMonth(dateObj).toISOString());
log("Selected: ", date.toISOString());
log("Next: ", dateNextMonth(dateObj).toISOString());
log("--------------");
}
const testCases = [
"2018-03-01 UTC",
"2018-03-31 UTC",
"2018-01-01 UTC",
"2018-12-31 UTC"
];
testCases.forEach(print);
Please note that the hack with new Date(xxx + " UTC") is not according to spec and is just there for testing purposes. Results may vary per browser.
You should choose an input format and construct your dates accordingly.
I handle it in a foolish way by concatenating string
let daysInMonths = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
let months = ["01", "02", "03", "04", "05", "06", "07", "08", "09", "10", "11", "12"];
var target = nexttarget = lasttarget = "29"; //target day
if (((year % 4 === 0) && (year % 100 !== 0)) || (year % 400 === 0)) {
daysInMonths[1] = 29;
}
function findLastDay(target, month){
if(target > daysInMonths[month]){
target = daysInMonths[month];
}
return target;
}
then
var d = new Date();
var year = d.getFullYear();
var month = d.getMonth();
target = findLastDay(target, month);
var this_month = year+"-"+months[month]+"-"+target;
console.log(this_month);//2018-03-29
// next month
if(month == 11){
nextmonth = 0;
nextyear = year + 1;
}else{
nextmonth = month+1;
nextyear = year;
}
nexttarget = findLastDay(nexttarget, nextmonth);
var next_month = nextyear+"-"+months[nextmonth]+"-"+nexttarget;
console.log(next_month);//2018-04-29
//last month
if(month == 0){
lastmonth = 11;
lastyear = year - 1;
}else{
lastmonth = month - 1;
lastyear = year;
}
lasttarget = findLastDay(lasttarget, lastmonth);
var last_month = lastyear+"-"+months[lastmonth]+"-"+lasttarget;
console.log(last_month);//2018-02-28
Date handling is tricky at the best of times. Don't do this yourself. Use Moment.js.
var target = 31;
var today = moment().date(target).calendar();
// today == '03/31/2018'
var nextMonth = moment().date(target).add(1, 'month').calendar();
// nextMonth == '04/30/2018'
var lastMonth = moment().date(target).subtract(1, 'month').calendar()
// lastMonth == '02/28/2018'

Check if Saturday and Sunday exist between two days in Javascript [duplicate]

Wondering if anyone has a solution for checking if a weekend exist between two dates and its range.
var date1 = 'Apr 10, 2014';
var date2 = 'Apr 14, 2014';
funck isWeekend(date1,date2){
//do function
return isWeekend;
}
Thank you in advance.
EDIT Adding what I've got so far. Check the two days.
function isWeekend(date1,date2){
//do function
if(date1.getDay() == 6 || date1.getDay() == 0){
return isWeekend;
console.log("weekend")
}
if(date2.getDay() == 6 || date2.getDay() == 0){
return isWeekend;
console.log("weekend")
}
}
Easiest would be to just iterate over the dates and return if any of the days are 6 (Saturday) or 0 (Sunday)
Demo: http://jsfiddle.net/abhitalks/xtD5V/1/
Code:
function isWeekend(date1, date2) {
var d1 = new Date(date1),
d2 = new Date(date2),
isWeekend = false;
while (d1 < d2) {
var day = d1.getDay();
isWeekend = (day === 6) || (day === 0);
if (isWeekend) { return true; } // return immediately if weekend found
d1.setDate(d1.getDate() + 1);
}
return false;
}
If you want to check if the whole weekend exists between the two dates, then change the code slightly:
Demo 2: http://jsfiddle.net/abhitalks/xtD5V/2/
Code:
function isFullWeekend(date1, date2) {
var d1 = new Date(date1),
d2 = new Date(date2);
while (d1 < d2) {
var day = d1.getDay();
if ((day === 6) || (day === 0)) {
var nextDate = d1; // if one weekend is found, check the next date
nextDate.setDate(d1.getDate() + 1); // set the next date
var nextDay = nextDate.getDay(); // get the next day
if ((nextDay === 6) || (nextDay === 0)) {
return true; // if next day is also a weekend, return true
}
}
d1.setDate(d1.getDate() + 1);
}
return false;
}
You are only checking if the first or second date is a weekend day.
Loop from the first to the second date, returning true only if one of the days in between falls on a weekend-day:
function isWeekend(date1,date2){
var date1 = new Date(date1), date2 = new Date(date2);
//Your second code snippet implies that you are passing date objects
//to the function, which differs from the first. If it's the second,
//just miss out creating new date objects.
while(date1 < date2){
var dayNo = date1.getDay();
date1.setDate(date1.getDate()+1)
if(!dayNo || dayNo == 6){
return true;
}
}
}
JSFiddle
Here's what I'd suggest to test if a weekend day falls within the range of two dates (which I think is what you were asking):
function containsWeekend(d1, d2)
{
// note: I'm assuming d2 is later than d1 and that both d1 and d2 are actually dates
// you might want to add code to check those conditions
var interval = (d2 - d1) / (1000 * 60 * 60 * 24); // convert to days
if (interval > 5) {
return true; // must contain a weekend day
}
var day1 = d1.getDay();
var day2 = d2.getDay();
return !(day1 > 0 && day2 < 6 && day2 > day1);
}
fiddle
If you need to check if a whole weekend exists within the range, then it's only slightly more complicated.
It doesn't really make sense to pass in two dates, especially when they are 4 days apart. Here is one that only uses one day which makes much more sense IMHO:
var date1 = 'Apr 10, 2014';
function isWeekend(date1){
var aDate1 = new Date(date1);
var dayOfWeek = aDate1.getDay();
return ((dayOfWeek == 0) || (dayOfWeek == 6));
}
I guess this is the one what #MattBurland sugested for doing it without a loop
function isWeekend(start,end){
start = new Date(start);
if (start.getDay() == 0 || start.getDay() == 6) return true;
end = new Date(end);
var day_diff = (end - start) / (1000 * 60 * 60 * 24);
var end_day = start.getDay() + day_diff;
if (end_day > 5) return true;
return false;
}
FIDDLE
Whithout loops, considering "sunday" first day of week (0):
Check the first date day of week, if is weekend day return true.
SUM "day of the week" of the first day of the range and the number of days in the lap.
If sum>5 return true
Use Date.getDay() to tell if it is a weekend.
if(tempDate.getDay()==6 || tempDate.getDay()==0)
Check this working sample:
http://jsfiddle.net/danyu/EKP6H/2/
This will list out all weekends in date span.
Modify it to adapt to requirements.
Good luck.

Creating a date validator

I'm trying to write a date validator that will take a date entered as a string of length 8 in the format ddmmyyyy. It needs to check it for all the basics for a valid date, and return either true or false as a result.
I am unable to use an additional library such as moment and I cannot use regular expressions (this is not a homework assignment, I'm just being told to work within these constraints).
I'd appreciate it if people could tell me what's wrong with what I have below!
function isValidDate(i) {
if (i.length == 8) {
var dd = i.substring(0, 2);
var mm = i.substring(2, 4);
var yyyy = i.substring(4, 7);
var day = parseInt(dd,10);
var month = parseInt(mm,10);
var year = parseInt(yyyy,10);
if (year % 4 != 0 && day = 29 && month = 02) {
return false;
} else if (day > 31) {
return false;
} else if (month > 12) {
return false;
} else {
return true;
}
} else {
return false;
}
return true;
}
You can use such function. This function checks if provided arguments is valid integer numbers (via parsing them to integer and checking if they not NaN) and then checks if month and days are valid, but doesn't validates year because year can be any number :)
function dateValidation(year, month, day){
// Check arguments
year = parseInt(year);
if (isNaN(year)) return false;
month = parseInt(month);
if (isNaN(month)) return false;
day = parseInt(day);
if (isNaN(day)) return false;
// Check if month is correct
if (!(month >= 1 && month <= 12)) return false;
switch (month){
case 1: //January
case 3: // March
case 5: // May
case 7: // July
case 8: // Augyst
case 10:// October
case 12:// December
return (day > 0 && day <= 31); // Maximum days is 31 in these months
break
case 4: // April
case 6: // June
case 9: // September
case 11:// November
return (day > 0 && day <= 30); // Maximum days is 30 in these months
break
case 2: // February
if (year % 4 != 0){
return (day > 0 && day <= 28);
} else {
return (day > 0 && day <= 29);
break
}
default:
return false;
}
}
Your first misstake is to use = instead of == in comparisation.
The next one is to use 02 as integer which is not possible because parseInt would make 2 out of 02 so just compare == 2
if (year % 4 != 0 && day == 29 && month == 2) {
An assignment will always return true in an if statement and year % 4 is not 0 in 2014 so you will always end up in "return false" until 2016

Check date in JavaScript

I get three variables through a user input, that contain the year of a date, the month and the day. I've already checked if the month var is between 1–12 and so on.
Now I want to check if it's a real date and not a date that doesn't exist like 31–06–2011.
My first idea was to make a new Date instance:
var year = 2011;
var month = 5; // five because the months start with 0 in JavaScript - June
var day = 31;
var myDate = new Date(2011,5,31);
console.log(myDate);
But myDate doesn't return false, because it's not a valid date. Instead it returns 'Fri Jul 01 2011 [...]'.
Any ideas how I can check for an invalid date?
Try this:
if ((myDate.getMonth()+1!=month)||(myDate.getDate()!=day)||(myDate.getFullYear()!=year))
alert("Date Invalid.");
if ((myDate.getDate() != day) ||
(myDate.getMonth() != month - 1) ||
(myDate.getFullYear() != year))
{
return false;
}
JavaScript just converts entered in Date constructor month, year, day, etc.. in simple int value (milliseconds) and then formats it to represent in string format. You can create new Date(2011, 100, 100) and everythig will ok :)
You could possibly do what you do now and construct a new Date object and then afterwards check the value of myDate.getFullYear(), myDate.getMonth(), myDate.getDate(), to ensure that those values match the input values. Keep in mind that getMonth() and getDate() are 0 indexed, so January is month 0 and December is month 11.
Here's an example:
function isValidDate(year, month, day) {
var d = new Date(year, month, day);
return d.getFullYear() === year && d.getMonth() === month && d.getDate() === day;
}
console.log(isValidDate(2011,5,31));
console.log(isValidDate(2011,5,30));
This is a old question question however to help me and other after me, here is a php checkdate solution from the following webpage:
https://locutus.io/php/datetime/checkdate/
function checkdate (m, d, y) {
return m > 0 && m < 13 && y > 0 && y < 32768 && d > 0 && d <= (new Date(y, m, 0))
.getDate()
}
I think this the right way to do it:
function isValidDate(year, month, day) {
var d = new Date(year, month, day)
if (month == 12) {
year = parseInt(year) * 1 + 1 * 1
month = 0
}
day = parseInt(day)
month = parseInt(month)
year = parseInt(year)
if (month === 2 && day > 29) {
return false
}
return (
d.getFullYear() === year && d.getMonth() === month && d.getDate() === day
)
}

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