Javascript date support
Coming from the python and mx.DateTime world, the javascript Date object is not really appealing. For me, the most disturbing things are :
- The year parameter in the Date constructor is always considered as a XXe century year if year < 100. (this goes along with the getYear / getFullYear distinction).
- The inconsistency between months and days indexes : months indexes starts at 0 whereas days indexes starts at 1.
- The lack of decent strptime / strftime functions (even basic ones not taking locales into account).
Recently, I've worked with the great Timeline project which makes an heavy use of dates and I had the need for a very basic strptime implementation. This can by no mean be considered as a comprehensive implementation, but it might help so here it is:
var _DATE_FORMAT_REGXES = {
'Y': new RegExp('^-?[0-9]+'),
'd': new RegExp('^[0-9]{1,2}'),
'm': new RegExp('^[0-9]{1,2}'),
'H': new RegExp('^[0-9]{1,2}'),
'M': new RegExp('^[0-9]{1,2}')
}
/*
* _parseData does the actual parsing job needed by `strptime`
*/
function _parseDate(datestring, format) {
var parsed = {};
for (var i1=0,i2=0;i1<format.length;i1++,i2++) {
var c1 = format[i1];
var c2 = datestring[i2];
if (c1 == '%') {
c1 = format[++i1];
var data = _DATE_FORMAT_REGXES[c1].exec(datestring.substring(i2));
if (!data.length) {
return null;
}
data = data[0];
i2 += data.length-1;
var value = parseInt(data, 10);
if (isNaN(value)) {
return null;
}
parsed[c1] = value;
continue;
}
if (c1 != c2) {
return null;
}
}
return parsed;
}
/*
* basic implementation of strptime. The only recognized formats
* defined in _DATE_FORMAT_REGEXES (i.e. %Y, %d, %m, %H, %M)
*/
function strptime(datestring, format) {
var parsed = _parseDate(datestring, format);
if (!parsed) {
return null;
}
// create initial date (!!! year=0 means 1900 !!!)
var date = new Date(0, 0, 1, 0, 0);
date.setFullYear(0); // reset to year 0
if (parsed.Y) {
date.setFullYear(parsed.Y);
}
if (parsed.m) {
if (parsed.m < 1 || parsed.m > 12) {
return null;
}
// !!! month indexes start at 0 in javascript !!!
date.setMonth(parsed.m - 1);
}
if (parsed.d) {
if (parsed.m < 1 || parsed.m > 31) {
return null;
}
date.setDate(parsed.d);
}
if (parsed.H) {
if (parsed.H < 0 || parsed.H > 23) {
return null;
}
date.setHours(parsed.H);
}
if (parsed.M) {
if (parsed.M < 0 || parsed.M > 59) {
return null;
}
date.setMinutes(parsed.M);
}
return date;
}
// and now monkey patch the Timeline's parser ...
/* provide our own custom date parser since the default
* one only understands iso8601 and gregorian dates
*/
Timeline.NativeDateUnit.getParser = function(format) {
if (typeof format == "string") {
if (format.indexOf('%') != -1) {
return function(datestring) {
if (datestring) {
return strptime(datestring, format);
}
return null;
};
}
format = format.toLowerCase();
}
if (format == "iso8601" || format == "iso 8601") {
return Timeline.DateTime.parseIso8601DateTime;
}
return Timeline.DateTime.parseGregorianDateTime;
};
