How to find unused/dead code in web projects (90% code in javascript)
Problem is there is no way to be really sure. Suppose the following:
- The initial HTML site is practically empty. There is a lot of JS code though, which seems to be unused.
- OnLoad, a function is called which launches an AJAX query to the server. The server returns a lot of HTML code, which is the body of the site. This body contains lots of JavaScript functions.
- The initial body is replaced with the body received via AJAX. Suddenly, all code is used.
Static analysis utilities are therefore useless. I do not know whether there exists a browser extension that marks all JS usage from a running browser though.
You can try using tombstones to safely locate and remove dead code from your JavaScript.
https://blog.bugsnag.com/javascript-refactoring-with-bugsnag-and-tombstones/
In order to find the unused assets, to remove manually, you can use deadfile library: https://m-izadmehr.github.io/deadfile/
It can simply find unused files, in any JS project.
Without any config, it supports ES6, JSX, and Vue files:
