js正则表达式验证时间格式是否正确

var reDateTime = /^(?:19|20)[0-9][0-9]-(?:(?:0[1-9])|(?:1[0-2]))-(?:(?:[0-2][1-9])|(?:[1-3][0-1])) (?:(?:[0-2][0-3])|(?:[0-1][0-9])):[0-5][0-9]:[0-5][0-9]$/;
var isDateTime = reDateTime.test('2018-08-17 09:16:22');