Function isLeapYear

codebase/sources/dhtmlxscheduler.es.js:15796–15798

(year)

var ORDINAL_BASE = datetime(1970, 1, 1);
var PY_WEEKDAYS = [6, 0, 1, 2, 3, 4, 5];
var isLeapYear = function(year) {
  return year % 4 === 0 && year % 100 !== 0 || year % 400 === 0;
};
var isDate = function(value) {
  return value instanceof Date;
};