Notepad++ is mostly used for editing source code, and all programming languages allow comments inside the source. So, this feature is possible to implement in all supported programming languages.
When a document (a source file) grows to large size, it becomes difficult to search inside the document and reach a specific section because for that you have to remember certain keywords and correct spellings of some words used specifically in that section of code. Strict adherence to your own naming conventions throughout the document or the whole project could be helpful a little going to the relevant part of the document, but this is not the ultimate solution.
The problem gets bigger in case of java script because a single file of the script is usually used to handle dozens of different pages and even the code is distributed in chunks and each chunk is independent and stand alone. (I am saying "a single file is used" because developers are getting more and more interested in serving a single js file for performance reasons. So, larger file, and difficult searching inside document.
One way that i can suggest for solving this problem is bookmarking inside document. For this,
1. notepad++ can parse comments inside documents to get hint. An example could be:
for php, js, C etc
/* NPP BOOKMARK "Force utf-8 conversion" */
<!-- NPP BOOKMARK "Top Navigation" -->
or something similar.
2. and, show a button on Toolbar, clicking which lists all the bookmarks on the page on a drop down menu. Clicking on a bookmark takes to the start of line of comment.
I do not use all plugin or builtin features of n++, so if such or similar feature exists, kindly let me know.
Hope my suggestion gets accepted and gets higher priority.