Question

I just finished my website, which I started 2 years ago. I was always trying new things, which sometimes included adding different frameworks or other external JS files.

Now I don’t know which of the linked files/lines of JS are unused. Is there a tool which can detect these files and lines of code? It would save me a lot of time.

Answer 1

This answer offers Google’s Closure Compiler which, in the process of minifying and concatenating your JavaScript code, can remove “dead code”.

Quoting from the documentation for the compilation levels:

Compilation with ADVANCED_OPTIMIZATIONS removes code that is provably unreachable. This is especially useful in combination with large libraries. If you use only a few functions from a large library file, the compiler can remove everything except those functions from its output.

Also see this answer which contains more information on Google’s Closure Compiler.