Highlighting HTML text

[C++ Programming]

I want to know any builtin function for highlighting a given keyword in HTML file.
Only the text outside of tags, comments, script code should be highlighted.

I think this could be done by :
Finding out the position of keyword which is a normal text
Replace it with keyword
Write the new content into the HTML file

Is there any standard method for doing the same?

Any suggestion would be greatly appreciable!!

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"Programming is an art that fights back!"