This is my 1st mini project using coffeescript dcaf.
Im currently doing some function in coffeescript, my roadblock is i cant compare 2 dates on if statement. Any thoughts?
In JavaScript (and also in CoffeeScript) the comparison operators (<,<=,==,>=,>,!=) are overloaded for the Date object.
Hence you can use something like this (in plain JavaScript):
var d1 = new Date();
var d2 = new Date();
if (d1 < d2) {
console.log("D1 is strictly before D2");
}
or like this (in CoffeeScript):
d1 = new Date()
d2 = new Date()
if d1 < d2
console.log "D1 is strictly before D2"
In both cases the underlying implementation is equivalent to a numeric comparison of the "epoch time" representation of the Date object - number of milliseconds since midnight (00:00:00) 1 January 1970 UTC - the same value returned by the getTime() method. So d1.getTime() < d2.getTime() would be an alternative way to express that comparison if you want to be more explicit about what is being compared.
Related
I was wondering if someone could help me.
I'm very new at ASP I want to format the current date and time as follows:
yyyy-mm-dd hh:mm:ss
But all i can do is the following
Response.Write Date
Can someone help me out please.
Date formatting options are limited in Classic ASP by default, there is a function FormatDateTime() which can format your date is various ways based on the servers regional settings.
For more control over date formatting though there are built in date time functions
Year(date) - Returns a whole number representing the year. Passing Date() will give back the current year.
Month(date) - Returns a whole number between 1 and 12, inclusive, representing the month of the year. Passing Date() will return the current month of the year.
MonthName(month[, abbv]) - Returns a string indicating the specified month. Passing in Month(Date()) as the month will give back the current Month string. As suggested by #Martha
Day(date) - Returns a whole number between 1 and 31, inclusive, representing the day of the month. Passing Date() will return the current day of the month.
Hour(time) - Returns a whole number between 0 and 23, inclusive, representing the hour of the day. Passing Time() will return the current hour.
Minute(time) - Returns a whole number between 0 and 59, inclusive, representing the minute of the hour. Passing Time() will return the current minute.
Second(time) - Returns a whole number between 0 and 59, inclusive, representing the second of the minute. Passing Time() will return the current second.
IMPORTANT:
When formatting date / time values, always store the date / time value first. Also, any needed calculations (DateAdd() etc.) should be applied before attempting to format or you will get unexpected results.
The functions Month(), Day(), Hour(), Minute() and Second() all return whole numbers. Luckily there is an easy workaround that lets you pad these values quickly Right("00" & value, 2) what it does is append 00 to the front of the value then from the right take the first two characters. This ensures that all single digit values return prefixed with a 0.
Dim dd, mm, yy, hh, nn, ss
Dim datevalue, timevalue, dtsnow, dtsvalue
'Store DateTimeStamp once.
dtsnow = Now()
'Individual date components
dd = Right("00" & Day(dtsnow), 2)
mm = Right("00" & Month(dtsnow), 2)
yy = Year(dtsnow)
hh = Right("00" & Hour(dtsnow), 2)
nn = Right("00" & Minute(dtsnow), 2)
ss = Right("00" & Second(dtsnow), 2)
'Build the date string in the format yyyy-mm-dd
datevalue = yy & "-" & mm & "-" & dd
'Build the time string in the format hh:mm:ss
timevalue = hh & ":" & nn & ":" & ss
'Concatenate both together to build the timestamp yyyy-mm-dd hh:mm:ss
dtsvalue = datevalue & " " & timevalue
Call Response.Write(dtsvalue)
Note: You can build the date string in one call but decided to break it down into the three variables to make it easier to read.
How Can I Format Date
Example of Parsing a Date String (Answers provide approaches to taking a date string format and parsing it to a valid Date variable).
Format the date of the previous day format yyyymmdd with VBScript (Example of why storing date / time before performing formatting is important)
VBScript ISO8601 (Example of functions to construct an ISO 8601 compliant date string)
Im just wondering. is it ok to combine years,month, and day of two date and make a comparison based on the combination.
eg:
Date A: 12th-January-2019
Date B: 24th-December-2018
Based on the above date, i could combine the year,month, and day as follow:
Date A: 20190112
Date B: 20181224
So based on the numbers, i could do logic like below to compare which date comes first:
if(Date A > Date B) {
output("Date A is the latest")
}
i would like to implement this method just to compare which is the latest date.
are there any problem of doing so.
java.time
Since you are using Java, I suggest that you take advantage of java.time, the modern Java date and time API.
String[] dateStringsFromDatabase = {
"2018/12/19",
"2017-02-01",
"2018.03.04",
"25-12-2016", // reversed
"2019\\09\\12",
"2014:03:01"
};
List<LocalDate> parsedDates = new ArrayList<>(dateStringsFromDatabase.length);
for (String dateString : dateStringsFromDatabase) {
// No matter which delimiter is used, replace it with a hyphen
String text = dateString.replaceAll("\\W", "-");
try {
parsedDates.add(LocalDate.parse(text));
} catch (DateTimeParseException dtpe) {
System.out.println(dateString + " not parsed: " + dtpe.getMessage());
}
}
Output:
25-12-2016 not parsed: Text '25-12-2016' could not be parsed at index 0
What this approach buys you is validation of the dates even though they come with all different delimiters. Especially in this situation I believe that you should want to validate that your strings are within the expected variations. Otherwise you risk that a date with the numbers reversed ends up as a date in year 2512, for example. You want to catch that before it happens.
Example of comparing which comes first:
for (int i = 1; i < parsedDates.size(); i++) {
LocalDate dateA = parsedDates.get(i - 1);
LocalDate dateB = parsedDates.get(i);
if (dateA.isAfter(dateB)) {
System.out.format("%s is later than %s%n", dateA, dateB);
}
}
Output:
2018-12-19 is later than 2017-02-01
2019-09-12 is later than 2014-03-01
Link: Oracle tutorial: Date Time explaining how to use java.time.
I'm adding a second to an instance of Foundation's date, but the result is off by an entire minute.
var calendar = Calendar(identifier: .iso8601)
calendar.locale = Locale(identifier: "en")
calendar.timeZone = TimeZone(identifier: "GMT")!
let date1 = Date(timeIntervalSinceReferenceDate: -62544967141.9)
let date2 = calendar.date(byAdding: DateComponents(second: 1),
to: date1,
wrappingComponents: true)!
ISO8601DateFormatter().string(from: date1) // => 0019-01-11T22:00:58Z
ISO8601DateFormatter().string(from: date2) // => 0019-01-11T21:59:59Z
Interestingly, one of the following makes the error go away:
round time interval since reference date
don't add time zone to calendar
set wrappingComponents to false (even though it shouldn't wrap in this case)
I don't really need sub-second precision in my code, so I created this extension that allows me to discard it.
extension Date {
func roundedToSeconds() -> Date {
return Date(timeIntervalSinceReferenceDate: round(timeIntervalSinceReferenceDate))
}
}
I want to know this:
Why does this error happen?
Am I doing something wrong?
Is there any issue with my workaround?
Why does this error happen?
I would say this is a bug in Core Foundation (CF).
Calendar.date(byAdding:to:wrappingComponents:) calls down to the internal Core Foundation function _CFCalendarAddComponentsV, which in turn uses the ICU Calendar C API. ICU represents a time as an floating-point number of milliseconds since the Unix epoch, while CF uses a floating-point number of seconds since the NeXT reference date. So CF has to convert its representation to ICU's representation before calling into ICU, and convert back to return the result to you.
Here's how it converts from a CF timestamp to an ICU timestamp:
double startingInt;
double startingFrac = modf(*atp, &startingInt);
UDate udate = (startingInt + kCFAbsoluteTimeIntervalSince1970) * 1000.0;
The modf function splits a floating-point number into its integer and fractional parts. Let's plug in your example date:
var startingInt: Double = 0
var startingFrac: Double = modf(date1.timeIntervalSinceReferenceDate, &startingInt)
print(startingInt, startingFrac)
// Output:
-62544967141.0 -0.9000015258789062
Next, CF calls __CFCalendarAdd to add one second to -62544967141. Note that -62544967141 lies in the round one-minute interval -62544967200 ..< -62544967140.0. So when CF adds one second to -62544967141, it gets -62544967140, which would be in the next round one-minute interval. Since you specified wrapping components, CF isn't allowed to change the minute part of the date, so it wraps back to the beginning of the original round one-minute interval, -62544967200.
Finally, CF converts the ICU time back to a CF time, adding in the fractional part of the original time:
*atp = (udate / 1000.0) - kCFAbsoluteTimeIntervalSince1970 + startingFrac + (nanosecond * 1.0e-9);
So it returns -62544967200 + -0.9000015258789062 = -62544967200.9, exactly 59 seconds earlier than the input time.
Am I doing something wrong?
No, the bug is in CF, not in your code.
Is there any issue with my workaround?
If you don't need sub-second precision, your workaround should be fine.
I can reproduce it with more recent dates but so far only with negative reference dates, e.g. Date(timeIntervalSinceReferenceDate: -1008899941.9), which is 1969-01-11T22:00:58Z.
Any negative timeIntervalSinceReferenceDate in the last second of a minute interval should cause the problem. The bug effectively makes the first round whole minute prior to time 0 span from -60.99999999999999 through -1.0, but it should span from -60.0 through -5e324. All more-negative round minute intervals are similarly offset.
I am accessing the SharePoint 2010 List WCF data service via DataJS and getting back date fields as /Date(1363708765000)/ does anyone have any idea how I can process this to display a proper date?
Note: I am posing here as I suspect this is a DataJS question more than a peculiarity of the ListData.svc in SharePoint.
What you're receiving back is a Unix epoch, which represents the number of milliseconds that have elapsed since Jan. 01 1970. Fortunately, JavaScript also uses this as its epoch, meaning you can create a new Date object using elapsed milliseconds as your input parameter:
var myDate = new Date(1363708765000);
console.log("UTC:" + myDate.toUTCString());
// outputs UTC: Tue, 19 Mar 2013 15:59:25 GMT
Of course, you'll have to parse out the integer portion of the date value you're getting back before you can use it to initialize a date. A reusable function might look like this:
function parseJsonDate( sDate ) {
var b, e, i;
b = sDate.indexOf('(');
e = sDate.indexOf(')');
i = sDate.substring(b+1,e);
if (isNaN(i)) { return null };
return new Date(parseInt(i));
}
I am using ColdFusion 9.0.1 and some database that I cannot change.
I am accessing a database that stores a date as an eight digit numeric with zero decimal places like this:
YYYYMMDD
I need to be able to read the date, add and subtract days from a date, and create new dates. I am looking for a ColdFusion solution to efficiently (not much code) to convert the date to our standard format, which is
MM/DD/YYYY
And then convert it back into the database's format for saving.
I need to code this in such a way that non-ColdFusion programmers can easily read this and use it, copy and modify it for other functions (such as adding a day to a date). So, I am not looking for the most least amount of code, but efficient and readable code.
Can you suggest anything that would make this code block more flexible, readable, or more efficient (less code)?
<cfscript>
// FORMAT DB DATE FOR BROWSER
DateFromDB = "20111116";
DatedToBrowser = createBrowserDate(DateFromDB);
writeOutput(DatedToBrowser);
function createBrowserDate(ThisDate) {
ThisYear = left(ThisDate, 4);
ThisMonth = mid(ThisDate, 4, 2);
ThisDay = right(ThisDate, 2);
NewDate = createDate(ThisYear, ThisMonth, ThisDay);
NewDate = dateFormat(NewDate, "MM/DD/YYYY");
return NewDate;
}
// FORMAT BROWSER DATE FOR DB
DateFromBrowser = "11/16/2011";
DateToDB = createDBDate(DateFromBrowser);
writeDump(DateToDB);
function createDBDate(ThisDate) {
ThisYear = year(ThisDate);
ThisMonth = month(ThisDate);
ThisDay = day(ThisDate);
NewDate = "#ThisYear##ThisMonth##ThisDay#";
return NewDate;
}
</cfscript>
First find who ever did the database and kick them in the nads...
Personally I'd Convert with sql so my code only dealt with date objects.
Select Convert(DateTime, Convert(VarChar(8),DateTimeInventedByIdjitColumn))
From SomeTable
As stated by our peers, store dates as dates.
'08/06/2011' could be 8th of june of the 6th of August depending on locale.
20111643 is a valid integer..
Not using a proper date type is just a massive collection of features and bugs that at best are waiting to happen.
You can actually rewrite each function into 1 line of code.
function createBrowserDate(ThisDate) {
return mid(ThisDate,4,2) & "/" & right(ThisDate,2) & "/" & left(ThisDate,4);
}
and
function createDBDate(ThisDate) {
return dateFormat( ThisDate, "YYYYMMDD" );
}
Don't keep dates as strings - keep dates as dates and format them when you need to.
If you can't correct the database to use actual date columns (which you should if you can), then you can use these two functions to convert to/from YYYYMMDD and a date object:
function parseYMD( YYYYMMDD )
{
if ( ! refind('^\d{8}$' , Arguments.YYYYMMDD ) )
throw "Invalid Format. Expected YYYYMMDD";
return parseDateTime
( Arguments.YYYYMMDD.replaceAll('(?<=^\d{4})|(?=\d{2}$)','-') );
}
function formatYMD( DateObj )
{
return DateFormat( DateObj , 'yyyymmdd' );
}
By using date objects it means that any level of developer can work with them, without needing to care about formatting, via built-in functions like DateAdd, DateCompare, and so on.
I'm not a regular expression fan since it's not that readable to me.
Since you're using CF9, I'd typed the argument and specify the returntype of the functions to be even more readable for the next person picking up your code.
First, right after I read the date from DB, I'd parse it to a Date object using parseDBDate()
Date function parseDBDate(required String dbDate)
{
var yyyy = left(dbDate, 4);
var mm = mid(dbDate, 4, 2);
var dd = right(dbDate, 2);
return createDate(yyyy , mm, dd);
}
Once you have the date object, you can use all those built-in Date functoin like DateAdd() or DateDiff().
Call browserDateFormat() right before you need to display it.
String function browserDateFormat(required Date date)
{
return dateFormat(date, "MM/DD/YYYY");
}
Call dBDateFormat() inside <cfqueryparam value=""> when it's time to persist to DB
String function dBDateFormat(required Date date)
{
return dateFormat(date, "YYYYMMDD");
}
One liner :)
myDateString = "20110203";
myCfDate = createObject("java","java.text.SimpleDateFormat").init("yyyyMMdd").parse(myDateString,createObject("java","java.text.ParsePosition").init(0*0));
If you want to parse different patterns, change "yyyyMMdd" to any other supported pattern.
http://download.oracle.com/javase/1.5.0/docs/api/java/text/SimpleDateFormat.html
The ParsePosition is used to say where to start parsing the string.
0*0 is shorthand for JavaCast("int",0) - in the Adobe cf engine, 0 is a string, until you apply math to it, then it becomes a Double, which the ParsePosition constructor supports. Technically, it constructs with an int, but cf is smart enough to downgrade a Double to an int.
http://download.oracle.com/javase/1.5.0/docs/api/java/text/ParsePosition.html