I think that the report will be useful to the participants of the conference. The fact is, any successful web application requires constant improvement and support, and it's quite difficult to do it on the frontend. In other words, everybody works with legacy code on the frontend, but there is no information how to do it.
It happened so that I had to change the assembly system for the company where I am currently working (Wrike). At the moment, there are more than 2,000,000 lines of code in our frontend repository. This report was born out of the experience with this array.
1) Refactoring definition;
2) Correct refactoring, when it is necessary to refactor and when it is not;
3) Refactoring and built-in IDE and editor tools;
4) Refactoring from the console, working with the source code as the text (grep), pitfalls, ideas, solutions;
5) Refactoring of styles. Pitfalls, ideas, solutions;
7) Gulp with the save.