If you find that your dog has not shown any symptoms after eating chocolate, you can take him to the hospital quickly and ask the doctor to induce vomiting. Just spit out the chocolate and it will be fine. Generally, there is no problem if you induce vomiting within two hours.
In addition, dogs cannot eat onions, scallions, xylitol, alcoholic foods, etc. to avoid acute poisoning. If you find that your dog has ingested toxic substances, you need to consult a pet doctor promptly.