How to link ThirdParty library for HTML5 build?

I have source code and precompiled lib files of some library.
To link this for Win32 or x64 library I just using standard method of linking through the .cs script.

But if I build my game with HTML5 compiler option I got many errors to log about unresolved external symbols.
How to solve this?

I must build library for HTML5 too? How to do it? Using cross compiler?

Thanks!