datepicker，结束时间必须大于开始时间

$('#js-start-time').datepicker({
	dateFormat:'yy-mm-dd',
	onSelect: function( startDate ) { var $startDate = $( "#js-start-time" ); var $endDate = $('#js-end-time'); var endDate = $endDate.datepicker( 'getDate' ); if(endDate < startDate){
			$endDate.datepicker('setDate', startDate - 3600*1000*24);
		}
		$endDate.datepicker( "option", "minDate", startDate );
	}
});
$('#js-end-time').datepicker({
	dateFormat:'yy-mm-dd',
	onSelect: function( endDate ) { var $startDate = $( "#js-start-time" ); var $endDate = $('#js-end-time'); var startDate = $startDate.datepicker( "getDate" ); if(endDate < startDate){
			$startDate.datepicker('setDate', startDate + 3600*1000*24);
		}
		$startDate.datepicker( "option", "maxDate", endDate );
	}
});