Validate Uk formatted date - javascript

I'm trying to validate a uk date using this code:
function ukdate(d) {
var p = new Date(d.split('/')[2], d.split('/')[1] -1, d.split('/')[0]);
if(p.toString() !== 'Invalid Date') {
return p;
}
}
http://jsfiddle.net/GE3xU/1/
so if I try ukdate('31/12/1981') it correctly returns "The Dec 31 1981". However if i try ukdate('12/31/1981') it returns "Tue Jul 12 1983".
Why is this happening? I'm expecting the second test to return invalid date because 31 is not a valid month.

JavaScript is converting your date for you.
In simple examples, you can get the last day of a given month by asking for the 0th day of the following month. Similarly, the "32nd of August" would be corrected to the 1st of September.
Months work similarly. The 13th month of a given year is the 1st month of the next. The 0th month of a year is December of the previous.
31 % 12 = 7, hence July, and floor(31/12) = 2 hence the year being shifted forward by two.
This is intended behaviour for JavaScript.
May I interest you in <input type="date" />? It uses whatever format is defined on the user's computer (ie. it is "locale-aware"), which is already excellent for user experience. On top of that, supporting browsers will render a calendar date picker, especially useful on phones too. Internally, the date is in "standard" YYYY-mm-dd format.

The month value is divided by 12 and added to the year, then the remainder is used as the actual month value.
See the spec
Let ym be y + floor(m /12).
Let mn be m modulo 12.

Related

Angular date issue

I have an object with a date property. I set the date to 01 April 2000 and can see in the debugger that it is set properly to the same date. However when I do a getMonth() on the same date object it returns month as 3 ( March ) . Why is this happening. Does it have anything to do with UTC or Localization both of which i am not using ?
You need +1 for getMonth function
var month = date.getMonth() + 1
this is normal behavior. Months starts with Zero(i.e january is 0). thats why its giving 3 for april. use adding 1 with month to get exact month's digit value.
i guess, to help indexing javascript starts month with zero.
suppose an array of months in string form then we dont have to worry to fetch correct month from string.

Don't allow convert to future year moment.js

I'm using moment.js to handle my date time values in my web application. I'm using follow format: DD.MM.YYYY for example 29.09.2016. Now I have some input fields, where I can type in the day of birth of a person. When I type a short year between 62 and 99, it converts it like this for example: input = 29.09.82 it converts it after pressing tab to 29.09.2082 (puts 20 befor the 82). When I write a short year between 00 and 62 in converts it like this example: input = 29.09.55 would be converted to 29.09.1955 (puts 19 before the 55). So the first range will be convertet to a year in the 21th century and the second range would be convertet to a year in the 20th century (this seems to be default, I don't know why). Now I would like to prevent converting to a year, which is in the future (so not more than 2016, and just 2016 when the short year is 16). How can I do this? At this moment I have something like this:
if(value.isValid() && isDayOfBirth) {
value.format(myFormat);
}
Is there a way to do this or to check it? I didn't found anything in the http://momentjs.com/docs/. Thanks.
This should work.
You take the current year and check if the parsed year is greater than that.
If so, you subtract 100 years (bringing you back to 20th century).
var now = moment(),
year = now.year(); //Get current year
if (parsedDate.year() > year) {
parsedDate.subtract(100, "year");
}

later.js - February and End of Month

I am creating a platform for recurring monthly orders.
I am using later.js for the recurrence. I have come across the following two cases and I am wondering if anybody has suggestions on how to better handle these (or if later.js handles them natively somehow):
later.parse.recur().on(31).dayOfMonth()
The date is the 31st of a given month. Current result is that is jumps months that end on the 30th. WORKAROUND: is to use last().dayOfMonth().
later.parse.recur().on(30).dayOfMonth()
later.parse.recur().on(31).dayOfMonth()
Month of February, ending on the 28th or 29th. How to handle if the date is 30th (or 31st). WORKAROUND: If date > 28th, add .and().on(59).dayOfYear()
Thanks!
I don't know the specifics of later.js, but apparently you can write something called a custom modifier: https://github.com/bunkat/later/blob/master/example/modifier.js
In addition to this, if you add a month to a javascript date (doesn't matter if the number becomes greater than 11/december), set the day of the month to the first then subtract 1 day, then you'll get the date of the last day in the originally given month. For example:
var a = new Date("2000-02-25");
var b = new Date(new Date(a.getFullYear(),a.getMonth()+1,1)-1);
console.log(b);

JavaScript: Convert Day/Week Into Year

I have been using Stack Overflow for a number of months now, but this is my first post.
I require a function to convert a week number and and day of week into a dd/mm/yyyy format.
The date values i have to work with are in the format day/weekNumber. So for example: 3/43 converts to Wednesday 24 October 20XX. The year value will be the current year.
The day value starts at 1 (Monday).
I have found lots of functions on the internet (such as this, this and this). Some work with ISO 8601 dates, which i do not think will work for me. And i have not yet found one that works for me.
Thanks in advance,
This solution does require an extra library to be added, but I think it is really worth it. It is a momentjs library for manipulating dates and time. It is actively maintained and has a great documentation. Once you get the values for day and weekNumber (in our case 3 and 43), you should do as follows:
function formatInput(day, weekNumber){
var currentDate = moment(new Date()); // initialize moment to a current date
currentDate.startOf('year'); // set to Jan 1 12:00:00.000 pm this year
currentDate.add('w',weekNumber - 1); // add number of weeks to the beginning of the year (-1 because we are now at the 1st week)
currentDate.day(day); // set the day to the specified day, Monday being 1, Sunday 7
alert(currentDate.format("dddd, MMMM Do YYYY")); // return the formatted date string
return currentDate.format("dddd, MMMM Do YYYY");
}
I think this library might be useful to you later on and there are plenty of possibilities regarding date and time manipulation, as well as formatting options. There is also a great documentation written for momentjs.
So assuming you have the values of 3 and 43 separately, you can just do some simple maths on the first day of the current year:
Get 1st January Current Year
Add (43 * 7 + 3)
Something like this maybe:
var currentDate = new Date();
var startOfYear = new Date(currentDate.getFullYear(), 0, 1);//note: months start at 0
var daysToAdd = (43 * 7) + 3;
//add days
startOfYear.setDate(startOfYear.getDate() + daysToAdd);
Here is an example
EDIT
On second thoughts, I think I was wrong with your requirements. It seems you require a specific day of the week. Check this out for a better solution.
The problem is that it all depends on your definition of a week. This year starts on a sunday, so does that mean that 02/01/2012 (the first monday of this year) is the start of the second week?
My latest example will first find the start of the specified week, and then find the next occurrence of the specified day
According to ISO when dealing with week dates, the week starts on Monday and the first week of the year is the one that contains the first Thursday of the year. So for 2012, the first week started on Monday, 2 January and the first week of 2013 will start on Monday, 31 December 2012.
So if 3/43 is the third day of the 43rd week (which is the ISO date 2012-W43-3), then it can be converted it to a date object using:
function customWeekDateToDate(s) {
var d, n;
var bits = s.split('/');
// Calculate Monday of first week of year this year
d = new Date();
d = new Date(d.getFullYear(),0,1); // 1 jan this year
n = d.getDay();
d.setDate(d.getDate() + (-1 * n +( n<5? 1 : 8)));
// Add days
d.setDate(d.getDate() + --bits[0] + --bits[1] * 7);
return d;
}
console.log(customWeekDateToDate('3/43')); // 01 2012-10-24
Note that this uses dates, otherwise daylight saving changeovers may result in the wrong date.

JS date() returning incorrect date

I'm am trying to format a date in Javascript but the date command is returning the wrong date unless I use toUTCString() which returns the correct date, I've tried different ways of giving the date to the Date() function and both get and getUTC functions to get the date. I've also tried on different browsers (Chrome, Safari, FireFox) and what makes in even more confusing is if I do it in Chrome's inspector is works perfectly. And I missing something obvious?
var d = new Date(1324141200000);
// return "Sat, 17 Dec 2011 17:00:00 GMT" - Correct!
alert(d.toUTCString());
// returns "6-11-2011" - Wrong!
alert(d.getUTCDay() +'-'+ d.getUTCMonth() +'-'+ d.getUTCFullYear());
The "getUTCDay()" function returns the day of the week. The months are numbered from zero. Saturday is the sixth day of the week (in JavaScript land at least), and 11 is the 12th month counting from zero.
Thus, all is well.
The day of the month can be retrieved with "d.getUTCDate()".
d.getUTCDay() // day of week
d.getUTCMonth() // zero based index
Instead of getUTCDay, you want getUTCDate. And getUTCMonth returns 0-11 (0 = January). Section 15.9.1 of the specification may help, but the language is heavy-going.
Use
getFullYear()
function to get the year,
getMonth()
function to get the month, and
getDate()
function to get the day.

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