When is it wise to use regular expressions with HTML? [closed]

Answer 1

Obviously, in the most simple cases like

Test

you might get along with a regex. But even then, a perfectly valid HTML tag could come in so many different varieties:

< A > Test                // match
< a href="test">   Test   // match
< A TEST="test"/>             // no match
< a href="test<">Test     // invalid input - catch that with a regex!

that the regex to catch them reliably gets HUGE. A DOM based parser will parse it, give you a proper error message if it fails, and provide stable results.