Develop Reference

How to convert a date formatted (YYMMDD) as string but with 00 days?

I have a date formatted as string, eg: 240800. The date format for that string is YYMMDD. With the below code, I can convert the string to date but it doesn't always work in deducting 1 day. I need my output to be a valid date, not with 00 day. So with the date above, it should be converted and formatted to 07/31/2024.
Here's what I got so far.
function formatDate(stringDate) {
var year = stringDate.substring(0,2);
var month = stringDate.substring(2,4);
var day = stringDate.substring(4,6);
var date = new Date('20' + year, month, day);
var formattedDate = date.getMonth() + '/' + date.getDate() + '/' + date.getFullYear();
console.log(formattedDate);
}
Working:
"240800" = 7/31/2024
All months from 4 to 12
Not Working:
"240100" = 0/31/2024 x
"240200" = 1/29/2024 x
"240300" = 2/31/2024 x

The reason is the date variable parameter in new Date() is counted as 0~11, not the general range,1~12.
So the working answer actually is wrong. It seems like being right just for July and August have 31 days.
The correct way is to firstly deduct 1 month and then calculate it. After all of the process is done, you can add 1 month in the end.
The below is working codes:
function formatDate(stringDate) {
var year = stringDate.substring(0,2);
//deduct 1 month firstly
var month = Number(stringDate.substring(2,4))-1;
var day = stringDate.substring(4,6);
var date = new Date('20' + year, month, day);
//add 1 month finally
var formattedDate = date.getMonth()+1 + '/' + date.getDate() + '/' + date.getFullYear();
console.log(formattedDate);
}
formatDate('240100');

In python Assuming your string is yymmdd below function should do what you want. I am sure javascript has some module for date handling.
from datetime import datetime, timedelta
def fd(s):
d=datetime.strptime(s[:-2],'%y%m')+timedelta(days=int(s[-2:])-1)
return d.strftime('%m/%d/%Y')

Try this ..
function formatDate(stringDate) {
var year = stringDate.substring(0,2);
var month = stringDate.substring(2,4);
var day = stringDate.substring(4,6);
var d1;
if (day==="00")
{
d1 = new Date(month + '/01/20' + year);
d1.setDate(d1.getDate() -1);
//console.log("day1" + d1);
}
else
{
d1 = new Date('20' + year, month, day);
}
var formattedDate = d1.getMonth() + '/' + d1.getDate() + '/' + d1.getFullYear();
console.log(formattedDate);
}

How can I convert timestamp to date format yyyy-MM-dd'T'HH:mm:ssXXX?

I would like to know if there's a way to convert a timestamp to yyyy-MM-dd'T'HH:mm:ssXXX date format?
I can convert it to ISO using toISOString but it add Z at the end of the string.
Thank you.

var d = new Date();
var datestring = d.getDate() + "-" +
(d.getMonth() + 1) + "-" +
d.getFullYear() + "-T " +
d.getHours() + ":" +
d.getMinutes();

If you really do not want to use an external library like moment.js (which i would strongly recommend), as you stated in your comment, you will have to implement a function for that yourself, as regular javascript does not provide a function for this (as far as i know).
You can create an object of javascripts built-in Date class from a unix timestamp by using
var unixTimestamp = 1566394163;
//multiply with 1000 as Date expects milliseconds
var date = new Date(unixTimestamp * 1000);
Then you could build the output string yourself, by using something along this
var dateString = "";
dateString += date.getUTCFullYear()+"-";
dateString += date.getUTCMonth()+"-";
dateString += ...
On the other hand, if the Z at the end of the string is the only thing that bothers you about the format provided by toISOString() as a workaround you could use its output and remove the last character of it
var dateString = date.toISOString();
var newDateString = dateString.substr(0, dateString.length -1);

Please try using below code to convert timestamp to date format.
var date = new Date(timestamp*1000);
var year = date.getFullYear();
var month = months_arr[date.getMonth()];
var day = date.getDate();
var hours = date.getHours();
var minutes = "0" + date.getMinutes();
var seconds = "0" + date.getSeconds();
Display date time in any format you want.

Converting Date time formats

What's the best way to convert date time formats using javascript?
I have this.. "2015-08-06T00:39:08Z"
and would like to change it to
"06/08/2015 12:39pm"

You could do it manually by instantiating a Date object:
var d = new Date('2015-08-06T00:39:08Z');
Then using the Date methods (like getDay or getUTCFullYear) to get the information needed and build the formatted string.
Or, if you don't mind relying on a library, you could use http://momentjs.com/ that provides a lot of methods, and particularly the format method: http://momentjs.com/docs/#/displaying/format/
// Example with moment.js
var formattedDate = moment('2015-08-06T00:39:08Z').format("MM/DD/YYYY hh:mma");
alert(formattedDate);

Use newDate() method, then Date Get Methods. Examples are explained on w3Schools
Method Description
getDate() Get the day as a number (1-31)
getDay() Get the weekday as a number (0-6)
getFullYear() Get the four digit year (yyyy)
getHours() Get the hour (0-23)
getMilliseconds() Get the milliseconds (0-999)
getMinutes() Get the minutes (0-59)
getMonth() Get the month (0-11)
getSeconds() Get the seconds (0-59)
getTime() Get the time (milliseconds since January 1, 1970)

With pure javascript:
code:
function formatDate(input) {
var datePart = input.match(/\d+/g),
year = datePart[0], // get only two digits
month = datePart[1],
day = datePart[2];
var h = parseInt(input.substr(input.indexOf("T") + 1, 2));
var m = parseInt(input.substr(input.indexOf(":") + 1, 2));
var dd = "AM";
if (h >= 12) {
h = hh - 12;
dd = "PM";
}
if (h == 0) {
h = 12;
}
m = m < 10 ? "0" + m : m;
alert(day + '/' + month + '/' + year + ' ' + h.toString() + ':' + m.toString() + dd);
}
formatDate('2015-08-06T00:39:08Z'); // "18/01/10"

Converting to a Date Object from a datetime-local Element

I am using the HTML5 element datetime-local. I need to have two formats of the date. One as a date object the other as a string. I am going to store the date object in the database and I am going to use the string to set the datetime-local form input.
I need to convert this string to a date object:
"2014-06-22T16:01"
I can't seem to get the correct time. This is what I am getting. The time not correct.
Sun Jun 22 2014 09:01:00 GMT-0700 (PDT)
This is the how I am formating the date:
function formatTime(_date) {
var _this = this,
date = (_date) ? _date : new Date(),
day = date.getDate(),
month = date.getMonth() + 1,
year = date.getFullYear(),
hour = date.getHours(),
minute = date.getMinutes(),
seconds = date.getSeconds(),
function addZero(num) {
return num > 9 ? num : '0' + num;
}
minute = addZero(minute);
seconds = addZero(seconds);
hour = addZero(hour);
day = addZero(day);
month = addZero(month);
return year + '-' + month + '-' + day + 'T' + hour + ':' + minute;
};
Example:
http://codepen.io/zerostyle/pen/gwpuK/

If you are trying to get an ISO 8601 date string, you can try Date.prototype.toISOString. However, it always uses UTC. If you want to include the local timezone, use something like the following:
/* Return a string in ISO 8601 format with current timezone offset
** e.g. 2014-10-02T23:31:03+0800
** d is a Date object, or defaults to current Date if not supplied.
*/
function toLocalISOString(d) {
// Default to now if no date provided
d = d || new Date();
// Pad to two digits with leading zeros
function pad(n){
return (n<10?'0':'') + n;
}
// Pad to three digits with leading zeros
function padd(n){
return (n<100? '0' : '') + pad(n);
}
// Convert offset in mintues to +/-HHMM
// Note change of sign
// e.g. -600 => +1000, +330 => -0530
function minsToHHMM(n){
var sign = n<0? '-' : '+';
n = Math.abs(n);
var hh = pad(n/60 |0);
var mm = pad(n%60);
return sign + hh + mm;
}
var offset = minsToHHMM(d.getTimezoneOffset() * -1);
return d.getFullYear() + '-' + pad(d.getMonth() + 1) + '-' + pad(d.getDate()) +
'T' + pad(d.getHours()) + ':' + pad(d.getMinutes()) + ':' + pad(d.getSeconds()) +
'.' + padd(d.getMilliseconds()) + offset;
}
console.log(toLocalISOString(new Date())); // 2014-06-23T07:58:04.773+0800
Edit
The above probably misses your question, which seems to be;
I need to convert this string to a date object: "2014-06-22T16:01"
Presumaly you want to treat it as a local time string. ECMA-262 says that ISO–like strings without a timezone are to be treated as UTC, and that is what your host seems to be doing. So you need a function to create a local Date object from the string:
function parseYMDHM(s) {
var b = s.split(/\D+/);
return new Date(b[0], --b[1], b[2], b[3], b[4], b[5]||0, b[6]||0);
}
console.log(parseYMDHM('2014-06-22T16:01')); // Sun Jun 22 16:01:00 UTC+0800 2014

javascript date of specific day of the week in MM/dd/yyyy format not libraries

I know there are a lot of threads about finding the date of a specific day of the week in javascript but the all give it in the format like so:
Sun Dec 22 2013 16:39:49 GMT-0500 (EST)
but I would like it in this format 12/22/2013 -- MM/dd/yyyy
Also I want the most recent Sunday and the code I have been using does not work all the time. I think during the start of a new month it screws up.
function getMonday(d) {
d = new Date(d);
var day = d.getDay(),
diff = d.getDate() - day + (day == 0 ? -6:0); // adjust when day is sunday
return new Date(d.setDate(diff));
}
I have code that gives me the correct format but that is of the current date:
var currentTime = new Date()
var month = currentTime.getMonth() + 1
var day = currentTime.getDate()
var year = currentTime.getFullYear()
document.write(month + "/" + day + "/" + year)
this prints:
>>> 12/23/2013
when I try to subtract numbers from the day it does not work, so I cannot get the dat of the most recent Sunday as MM/dd/yyyy
How do I get the date of the most recent sunday in MM/dd/yyyy to print, without using special libraries?

You can get the current weekday with .getDay, which returns a number between 0 (Sunday) and 6 (Saturday). So all you have to do is subtract that number from the date:
currentTime.setDate(currentTime.getDate() - currentTime.getDay());
Complete example:
var currentTime = new Date()
currentTime.setDate(currentTime.getDate() - currentTime.getDay());
var month = currentTime.getMonth() + 1
var day = currentTime.getDate()
var year = currentTime.getFullYear()
console.log(month + "/" + day + "/" + year)
// 12/22/2013
To set the date to any other previous weekday, you have to compute the number of days to subtract explicitly:
function setToPreviousWeekday(date, weekday) {
var current_weekday = date.getDay();
// >= always gives you the previous day of the week
// > gives you the previous day of the week unless the current is that day
if (current_weekday >= weekday) {
current_weekday += 6;
}
date.setDate(date.getDate() - (current_weekday - weekday));
}
To get the date of next Sunday you have to compute the number of days to the next Sunday, which is 7 - currentTime.getDay(). So the code becomes:
currentTime.setDate(currentTime.getDate() + (7 - currentTime.getDay()));

Subtract days like this
// calculate days to subtract as per your need
var dateOffset = (24*60*60*1000) * 5; //5 days
var date = new Date();
date.setTime(date.getTime() - dateOffset);
var day = date.getDate() // prints 19
var month = date.getMonth() + 1
var year = date.getFullYear()
document.write(month + '/' + day + '/' + year);

Here is my suggestion. Create a function like so... in order to format any date you send it.
function formatDate(myDate) {
var tmp = myDate;
var month = tmp.getMonth() + 1;
var day = tmp.getDate();
var year = tmp.getFullYear();
return (month + "/" + day + "/" + year);
}
Now, to print the current date, you can use this code here:
var today = new Date();
var todayFormatted = formatDate(today);
To get the previous Sunday, you can use a while loop to subtract a day until you hit a Sunday, like this...
var prevSunday = today;
while (prevSunday.getDay() !== 0) {
prevSunday.setDate(prevSunday.getDate()-1);
}
var sundayFormatted = formatDate(prevSunday);
To see the whole thing together, take a look at this DEMO I've created...
** Note: Make sure you turn on the Console tab when viewing the demo. This way you can see the output.

You can create prototype functions on Date to do what you want:
Date.prototype.addDays = function (days) {
var d = new Date(this.valueOf());
d.setDate(d.getDate() + days);
return d;
}
Date.prototype.getMostRecentPastSunday = function () {
var d = new Date(this.valueOf());
return d.addDays(-d.getDay()); //Sunday is zero
}
Date.prototype.formatDate = function () {
var d = new Date(this.valueOf());
//format as you see fit
//http://www.webdevelopersnotes.com/tips/html/10_ways_to_format_time_and_date_using_javascript.php3
//using your approach...
var month = d.getMonth() + 1
var day = d.getDate()
var year = d.getFullYear()
return month + "/" + day + "/" + year;
}
console.log((new Date()).getMostRecentPastSunday().formatDate());
console.log((new Date("1/3/2014")).getMostRecentPastSunday().formatDate());
//or...
var d = new Date(); //whatever date you want...
console.log(d.getMostRecentPastSunday().formatDate());

Something like this will work. This creates a reusable dateHelper object (you will presumably be adding date helper methods since you don't want to use a library off the shelf). Takes in a date, validates that it is a date object, then calculates the previous Sunday by subtracting the number of millis between now and the previous Sunday.
The logging at the bottom shows you how this works for 100 days into the future.
var dateHelper = {
getPreviousSunday: function (date) {
var millisInADay = 86400000;
if (!date.getDate()) {
console.log("not a date: " + date);
return null;
}
date.setMilliseconds(date.getMilliseconds() - date.getDay() * millisInADay);
return date.getMonth() + 1 + "/" + date.getDate() + "/" + date.getFullYear();
}
}
var newDate = new Date();
console.log(dateHelper.getPreviousSunday(newDate));
var now = newDate.getTime();
for (var i=1; i<100; i++) {
var nextDate = new Date(now + i * 86400000);
console.log("Date: + " nextDate + " - previous sunday: " + dateHelper.getPreviousSunday(nextDate));
}