date input manipulation

validate_date.js

/**
   *
   * @param date {string}
   * @returns {string || null}
   */
  function validateDate (date) {
    var dateError = false;
    //console.log("VALIDATE DATE = "+ date)
    if (date) {
      var sDate = date.split(/[.,\/ -]/);
      var sDay = sDate[0];
      var sMonth = sDate[1];
      var sYear = sDate[2];
      if (sDay) {
        if (isNaN(sDay)) dateError = true;
      }
      if (sMonth) {
        if (isNaN(sMonth)) dateError = true;
      } else {
        sMonth = new Date().getMonth() + 1;
      }

      if (sYear) {
        if (isNaN(sYear)) { dateError = true;
        } else {
          if (sYear < 100) {
            if (sYear < 50) { sYear = 2000 + parseInt(sYear);
            } else {          sYear = 1900 + parseInt(sYear);
            }
          }
        }
      } else {
        sYear = new Date().getFullYear(); // fix bug : if month = 0 and year = 0 -> month <> january
      }
      //console.log({year: sYear, month: sMonth - 1, day: sDay});
      if (!dateError && (!moment({year: sYear, month: sMonth - 1, day: sDay}).isValid()) ) dateError = true;
    } else { //Invalide Date
      dateError = true;
    }
    return !dateError ? moment({year: sYear, month: sMonth - 1, day: sDay}).format("DD/MM/YYYY").toString() : null;
  }