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My choir wants to advertise the number of rehearsals before the next concert on their website.

The problem

My choir wants to advertise the number of rehearsals before the next concert. We have a list of rehearsal dates and need to count those who have not yet passed.

The solution (JavaScript)

<div id="result"></div>
function dateDtoE(s)
  h = s.split(".");
  return '20' + h[2] + '-' + ('0'+h[1]).substr(-2) + '-' + ('0'+h[0]).substr(-2); 
var dates2go = [ '28.6.18','5.7.18','12.7.18','19.7.18','26.7.18','2.8.18','9.8.18','30.8.18'];

var count = 0;
var now = new Date();
var i = dates2go.length;
  h = dateDtoE(dates2go[i]);
  var test = new Date(dateDtoE(dates2go[i]) + 'T22:00:00');
  if(test > now)
document.getElementById('result').innerHTML = '<p>Still ' + count + ' rehearsals!</p>';

The function dateDtoE converts a date from German format to javascript format, ie. from 13.6.18 to 2018-06-13.

When creating a Date object from the list of dates, the script assumes 10 p.m. as time of day. This is when our rehearsals usually end.

Note the use of a while loop. Lazybones might have used for(i=0;i<dates2go.length;i++), thus recounting the number of elements in the array for every iteration of the loop.

Extra: A solution in Ruby

I know next-to-nothing about ruby, sorry.

require 'time'

def dateDtoE(s)
  h = s.split('.');
  return '20' + h[2] + '-' + h[1] + '-' + h[0]

dates2go = ['28.6.18','5.7.18','12.7.18','19.7.18','26.7.18','2.8.18','9.8.18','30.8.18']
count = 0
now = Time.now()
dates2go.each{ |d|
  h = Time.parse(dateDtoE(d));
  if h > now 
    count += 1
puts "Still #{count} rehearsals."

Note how the loop looks more elegant. Furthermore, ruby’s date parser doesn’t rely on leading zeros.