“Mr. Trump would be fired for his tweets of today, and nearly every day,” said Mike Driehorst, a social media expert at the marketing agency Weaving Influence. “Most companies have a thin skin when it comes to public criticism and media reports.”

Nannina Angioni, an employment attorney at the Los Angeles-based law firm Kaedian, said certain speech is protected, such as posts about a workplace grievance or organizing a union. But she said that if “you take to Twitter to call your boss a ‘psycho’ or say that your CEO has a ‘low I.Q.’ that could absolutely get you fired.”

That applies even to chief executives.