Re: dd/mm/yyyy Date Compare Problem

JRS: In article <e2uf60015o6@xxxxxxxxxxxxxxxxx>, dated Fri, 28 Apr 2006
20:23:07 remote, seen in news:comp.lang.javascript, Matt Kruse
<newsgroups@xxxxxxxxxxxxx> posted :
Dr John Stockton wrote:

I've re-written my date code recently to extend Date using prototypes for
most functions. One thing you might not like is that I don't use regular
expressions to parse text. Instead, I still use the manual substring
approach. Someday I'll update it further, but it's solid as-is, and I don't
have a lot of time, so updating working code doesn't seem like the best use
of it :)

it might be
quite easy to produce, in javascript, a de-commenter and de-indenter.
Your library could be fetched in its full glory, but readily reduced
to the working parts without positive obfuscation.
...But perhaps you already have something better.

I do this in real-time in PHP, actually.
...

I did mean that the de-*er would be distributed, for example on a web
page; then the material could be sent in full from library author to
each Web programmer, who could retail a full-glory reference copy but
use in pages the reduced version.

Since you read offline, I'll paste my source below in case you want to look
at it. I'm always open to suggestions, although I can probably already name
many of the same ones that you might offer ;) Hope the code isn't too long,
and of course beware of wrapping.

/*
Date functions

These functions are used to parse, format, and manipulate Date objects.
See documentation and examples at http://www.JavascriptToolbox.com/lib/date/

*/
Date.$VERSION = 1.01;

Quote pruned.

// Utility function to append a 0 to single-digit numbers
Date.LZ = function(x) {return(x<0||x>9?"":"0")+x};

x<0|| is probably not needed in this contest; but prudent.


Date.dayAbbreviations = new
Array('Sun','Mon','Tue','Wed','Thu','Fri','Sat');

Add a Sunday at the end of the week, and you can match ISO 8601 too!


// If the getFullYear() method is not defined, create it
if (!Date.prototype.getFullYear) {
Date.prototype.getFullYear = function() { var yy=this.getYear(); return
(yy<1900?yy+1900:yy); }
}

I have heard that there is or has been a browser which, at least in
1900..2099, has getYear() returning Year%100, for which that fails. See
js-date0.htm, #gY, #gFY. OTOH, if your library is in use in conjunction
with such a browser, the problem will have been noticeable for six
years.


this.isInteger = function(val) {
for (var i=0; i < val.length; i++) {
if ("1234567890".indexOf(val.charAt(i))==-1) {
return false;
}
}
return true;
};

or this.isInteger = function(val) { return !/\D/.test(val) }
and name could be isNonNegInt. ISTM that both fail on empty strings;
unary + seems to accept an empty string as 0, but parseInt gives NaN.



// Is date valid for month?
if (month==2) {
// Check for leap year
if ( ( (year%4==0)&&(year%100 != 0) ) || (year%400==0) ) { // leap year
if (date > 29){
return null;
}
}
else {
if (date > 28) {
return null;
}
}
}

There's no need to evaluate Leapness unless it's Feb 29. Feb <29 is
always good; Feb >29 always bad.

I'd use Date Object readback, or an array [0,31,28,31,...,31] to look up
the maximum date for the month, then if date > maximum then if date = 29
then OK = Leap.



// Clear all time information in a date object
Date.prototype.clearTime = function() {
this.setHours(0);
this.setMinutes(0);
this.setSeconds(0);
this.setMilliseconds(0);
return this;
}

setTing can be combined in JS 1.3+


// Add an amount of time to a date. Negative numbers can be passed to
subtract time.

However, the amount of time actually added can depend on the date; Years
and Feb vary in length by a day, and days can vary by an hour.


Date.prototype.add = function(interval, number) {

else if (interval=='w') { // Weekday

I think you are adding a number of WORKING days, stepwise. You could do
div and mod 5, then add 7 times the div result and step the mod result.
It would be faster for long intervals.

var step = (number>0)?1:-1;
while (number!=0) {
this.add('d',step);
while(this.getDay()==0 || this.getDay()==6) {
this.add('d',step);
}
number -= step;
}
}


Adding Minutes, Seconds could be appreciably faster with setTime (but
then Minutes sometimes wrong for Lord Howe Island).


You have support for FIPS/ISO elsewhere?

--
© John Stockton, Surrey, UK. ?@merlyn.demon.co.uk Turnpike v4.00 IE 4 ©
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