Trying to setup a new Date() object is a pain in the ass!

weirdDateBehaviour.js

// Stupid JavaScript Date inconsistency

//So, Say you have a string Date

var lastDayOf2010 = "2010-12-31";
var choppedLastDayOf2010 = lastDayOf2010.split('-');

// Let's say you decide to parse the date like so:

var badDate = new Date(
  choppedLastDayOf2010[0], 
  choppedLastDayOf2010[1], 
  choppedLastDayOf2010[2]
);

//> Mon Jan 31 2011 00:00:00 GMT+0000 (GMT)

// wtf?
//
// Turns out that to pass a month into the new Date() 
// argument, you have to pass in a number between 0 
// (for January) and 11 (for December).
// 
// So, to get the correct date, I have to do this:
//
// 

var correctDate = new Date(
  choppedLastDayOf2010[0], 
  choppedLastDayOf2010[1] - 1, 
  choppedLastDayOf2010[2]
);

//> Fri Dec 31 2010 00:00:00 GMT+0000 (GMT)

// So you would imagine the same rule would apply to 
// the day (with 0 being the first day of a month), 
// but it doesn't:

var wtfDate = new Date(
  choppedLastDayOf2010[0], 
  choppedLastDayOf2010[1] - 1, 
  0
);

//> Tue Nov 30 2010 00:00:00 GMT+0000 (GMT)

// It seems inconsistent, and is a pain in the ass!

// Alternatively, you can use the Date.parse() method to 
// convert the lastDayOf2010 string variable into a number 
// representing unix epoch time, and then pass the number 
// into the new Date() code:

var goodDate = new Date(Date.parse(lastDayOf2010));

// 2011. Paul Jensen

I think the month is from 0 to 11 so you could have the month names in an array and do monthNames[date.getMonth()].

It is still very weird though!

Agreed, oh well, at least there's Date.parse().

Hope all is going well over in Clerkenwell.