Write a small js script

Web programmer services are required. We need to write a js script. That's the point. The js script itself is placed in the code of landing pages or sites and when called in the browser, enters cookies into the user's browser and attaches to me as a referral. In a word, it is necessary that the script attaches a person to me with referral connections, and in the future this person will be my referral. You need to make sure that the person does not know about it, and that the browser does not warn him about it. No data from users is not necessary to steal. Just stick it like a referral. Sori can't explain what I'm saying in professional language. I'm waiting for feedback.