Yes, that’s possible, it may be that the standard is now to use .o files instead of .bc. Alternatively, .a files (which are really just archives containing .o files) may be used.
I’m using the ability of FreezeTool to produce an executable. Or rather, FreezeTool thinks it’s producing an executable, when it’s actually telling emscripten to produce a .js file that can be embedded in the browser. Producing the .c file is an intermediary step in that process, but it should get you a .js as output.