function startOfMonth(dirtyDate) {
  __WEBPACK_IMPORTED_MODULE_1__lib_requiredArgs_index_js__["a" /* default */](1, arguments);
  var date = __WEBPACK_IMPORTED_MODULE_0__toDate_index_js__["a" /* default */](dirtyDate);
  date.setDate(1);
  date.setHours(0, 0, 0, 0);
  return date;
}
@name startOfMonth
@category Month Helpers
@summary Return the start of a month for the given date.

@description
Return the start of a month for the given date.
The result will be in the local timezone.

### v2.0.0 breaking changes:

- [Changes that are common for the whole library](https://github.com/date-fns/date-fns/blob/master/docs/upgradeGuide.md#Common-Changes).

@param {Date|Number} date - the original date
@returns {Date} the start of a month
@throws {TypeError} 1 argument required

@example
// The start of a month for 2 September 2014 11:55:00:
var result = startOfMonth(new Date(2014, 8, 2, 11, 55, 0))
//=> Mon Sep 01 2014 00:00:00