How to display dates in a given range, specific days of the week?

Question

JavaScript

How to display dates of given days of the week before a certain date? For example:
Tuesday + Wednesday: 07/18/17 07/19/17 07/25/17 07/26/17 . . .
Monday + Friday: 07/17/17 07/21/17 07/24/17 07/28/17 . . .
etc.
The days of the week are selected by the user.

Answer 1

The Date object 's setDate() method sets the day of the month, updating the month as necessary.
Those. the algorithm is simple: add 7 days to the included days of the week, and read the resulting date.

More or less like this:

/**
 * Make Dates according to selected days of week till the specified date
 * @param Array weekdays: 0 - Sunday, 1 - Monday, ..
 * @param Mixed Date or String - last day of range
 *
 * @return Array of Date objects
 */
function getDates( weekDays, lastDate) {
  if(typeof lastDate === 'string') lastDate = new Date(lastDate);
  
  var today = new Date(), dow, i, D, datesPool = [], result = [];
  today.setHours(0);
  today.setMinutes(0);
  today.setSeconds(0);
  dow = today.getDay(); 
  for(i=0; i<7; i++) {
    if( !~weekDays.indexOf( (dow + i)%7)) continue;
    D = new Date();
    D.setTime( today.getTime());
    D.setDate( D.getDate() + i);
    if( D.getTime() > lastDate.getTime()) continue;
    datesPool.push( D);
  }
  
  if( datesPool.length === 0) return result;
  
  while(true) {
    for( i = 0; i < datesPool.length; i++) {
      D = datesPool[i];
      if( D.getTime() > lastDate.getTime()) return result;
      if( result.length > 1000) return result;
      result.push( "" + D.getDate() + "." + (1 + D.getMonth()) + "." + D.getFullYear().toString().substr(2));
      D.setDate( D.getDate() + 7);
    }
  }
}

getDates( [2,3], '2017-07-31') // 19.7.17,25.7.17,26.7.17

Answer 2

Use moment.js