Very clever if you reduce the hash, eg quicker redirect
https://coin-hive.com/
Very cool concept, but boy do you need to put some numbers through. Testing we just ran here suggested 36 days of processor time to earn $1 . Ouch
Moderate traffic site getting 50k visits per day and 1 minute of mining time per user would earn about a dollar a day.
(all based on 17 processor running 5 threads)
Don't try to compete...