What you're describing is a recognizer, not a parser. A parser by definition produces some output other than a boolean 'yes, this is a syntactically correct HTM

What you're describing is a recognizer, not a parser. A parser by definition produces some output other than a boolean 'yes, this is a syntactically correct HTML/JS input' (which is still more useful than what a tokenizer/scanner gives you, which is 'yes, this thing contains only HTML/JS tokens and here they are...splat')