Sort array of days in javascript

const days = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"];

const sortDays = function (a, b) {
  a = days.indexOf(a);
  b = days.indexOf(b);
  return a < b ? 0 : 1;
};

const myArrayOfDays = ["Tuesday", "Saturday", "Monday", "Thursday"].sort(sortDays);
// returns ["Monday", "Tuesday", "Thursday", "Saturday"];

function sort_days(days) {

To get today's day of week, use new Date().getDay(). This assumes Sunday = 0, Monday = 1, ..., Saturday = 6.

    var day_of_week = new Date().getDay();

To generate the list of the days of week, then slice the list of names:

    var list = ["Sun","Mon","Tue","Wed","Thu","Fri","Sat"];
    var sorted_list = list.slice(day_of_week).concat(list.slice(0,day_of_week));

(today is Friday, so sorted_list is ['Fri','Sat','Sun','Mon','Tue','Wed','Thu'])

Finally, to sort, use indexOf:

    return days.sort(function(a,b) { return sorted_list.indexOf(a) > sorted_list.indexOf(b); });
}

Putting it all together:

function sort_days(days) {
    var day_of_week = new Date().getDay();
    var list = ["Sun","Mon","Tue","Wed","Thu","Fri","Sat"];
    var sorted_list = list.slice(day_of_week).concat(list.slice(0,day_of_week));
    return days.sort(function(a,b) { return sorted_list.indexOf(a) > sorted_list.indexOf(b); });
}