Get next date from weekday in JavaScript

Question

Dear coding gurus,

would you be so kind and tell me if this is possible in JavaScript to return the next date of given weekday (it could be either a number 0-6 or names Sunday-Saturday).

Example, if today, on 16-Oct-2009 I passed in:

• Friday, it would return today's date 16-Oct-2009
• Saturday returned 17-Oct-2009
• Thursday returned 22-Oct-2009

Thanks, I really hope to get an answer and people, who search for this kind of function on-line would end up here, since I haven't found anything else out there that solves this. This, indeed ain't rent-a-coder, because the solution is accessible to everyone for free! I don't think you need to comment if you don't know the answer, I do, however, appreciate your comments (@Andy & @Josh).

Answer 1

Just adding 7 doesn't solve the problem.

The below function will give you the next day of the week.

function nextDay(x){
    var now = new Date();    
    now.setDate(now.getDate() + (x+(7-now.getDay())) % 7);
    return now;
}

Answer 2

To expand on user 190106's answer, this code should give you what you wanted:

function getNextDay(day, resetTime){
  var days = {
    sunday: 0, monday: 1, tuesday: 2,
    wednesday: 3, thursday: 4, friday: 5, saturday: 6
  };

  var dayIndex = days[day.toLowerCase()];
  if (!dayIndex) {
    throw new Error('"' + day + '" is not a valid input.');
  }

  var returnDate = new Date();
  var returnDay = returnDate.getDay();
  if (dayIndex !== returnDay) {
    returnDate.setDate(returnDate.getDate() + (dayIndex + (7 - returnDay)) % 7);
  }

  if (resetTime) {
    returnDate.setHours(0);
    returnDate.setMinutes(0);
    returnDate.setSeconds(0);
    returnDate.setMilliseconds(0);
  }
  return returnDate;
}

alert(getNextDay('thursday', true));

Answer 3

A swiss-knife tool for javascript DateTime programming.

http://www.datejs.com/