Regex to disallow more than 1 dash consecutively

Question

1. How can I disallow -- (more than 1 consecutive -)? e.g. ab--c
2. - at the back of words not allow, e.g. abc-<

Answer 1

If “-” is not allowed at the beginning nor end of the string, you are searching for a sequence of “one or more alanum, followed by one or more group(s) of one dash followed by 1 or more alanum”

/[0-9A-Z]+(-[0-9A-Z]+)+/

Simple is a valuable motto with regular expressions. (nota : to search small case characters, add them. I didn't for clarity)