How to find and replace some combinations of letters and numbers in an html document with others?

Question

HTML

There is a large, just huge, html document. The document contains combinations of letters and numbers of the form:
code_X, where code is a certain constant, the same text, and X is a combination of letters and numbers, each time different. Well, for example:
code_123or code_АБВor code_34ВА3ВАВА834
All phrases of the form code_XI need to replace with others, conditionally new_code. That is, so that and code_123and code_АБВand code_34ВА3ВАВА834turns into new_code.
How can this be done in the best possible way? In addition to HTML and CSS, I only know the basics of js. :(

Answer 1

code_\w*
You can practice here

Answer 2

Regular expressions and text editor.