正则表达式如何匹配递增数字

Question

正则表达式如何匹配6位数为这种数字格式？
123123
234234
345345

Answer 1

/^(123|234|345|456|678|789)\1$/g

Answer 2

var aabbcc = /^(?:(\d)\1)+$/;
var ababab = /(\d{2})\1+$/;
var abcabc = /^(\d{3})\1+$/;
var aaabbb = /^(?:(\d)\1\1)+$/;

Answer 3

(\d{3})\1