regex to match repeated consonant

Question

How can I detect with a regex expression if the same consonant is repeated three times or more?

My idea is to match words like tttoo

Answer 1

Try this:

([b-df-hj-np-tv-z])\1{2,}

Explanation:

• [b-df-hj-np-tv-z] are all the consonants
• \1 is the back reference to the 1st group (ie the same character)
• {2,} means "2 or more of the preceding term", making 3 or more in all

See live demo.