strings (and replace method…

Hi all new on here..
I know that the test /regular expressions works with web page text….but i am new to javasript …
is it possible to test for a reg expression in a (well actually using a full blown) start to finish div tag and then replace the whole div and content using the replace() method…..
didn’t know whether or not the replacing strings busines can be done with html tags (CAN IT?)?

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