Is it possible to implement a miner on the site?

Question

Law in IT

When a user enters the site, the mining script is immediately launched, but the entire page of the site will be written about the use of your resources.
Is this allowed?

Answer 1

Firefox blocks this, Chrome probably does too.
Users from such sites are dumped immediately, cursing the little schoolboy.
UPD: answering the question: yes, it's legal.

Answer 2

Even if you do not write, what is illegal? Or after how many percent of the CPU time the legitimacy stage changes. Or do you think if the site makes money on you, then it's not legal? So then 99% of the sites should be blocked.