date-range-picker.js

// Convert the format string from moment's "L" to a format usable by
// [bootstrap-datepicker][1].
//
// Call it with:
//
// momentFormatToDatePicker(moment.localeData().longDateFormat("L")).
//
// [1]: https://bootstrap-datepicker.readthedocs.org/en/latest/options.html#format
function momentFormatToDatePicker(format) {
  // The actual translation is more detailed:
  // | Moment | Date Picker | Used by "L" |
  // |--------|-------------|-------------|
  // | MMMM   | MM          | ✘ No        |
  // | MMM    | M           | ✘ No        |
  // | MM     | mm          | ✔ Yes       |
  // | M      | m           | ✘ No        |
  // | Mo     | m           | ✘ No        |
  // | DDDD   | DD          | ✘ No        |
  // | DDD    | D           | ✘ No        |
  // | DDDo   | D           | ✘ No        |
  // | DD     | dd          | ✔ Yes       |
  // | D      | d           | ✔ Yes       |
  // | Do     | d           | ✘ No        |
  // | YYYY   | yyyy        | ✔ Yes       |
  // | YY     | yy          | ✔ Yes       |
  // However, of the 72 languages supported by Moment none of them use the
  // exetended formats for their localized "L" and of the formats used a simple
  // toLowerCase() covers the conversion we need. This chart left for future
  // concideration if more advanced conversions are required.
  return format.toLowerCase();
}