Do you know what it means? A lingua franca is able to facilitate communication between many parties who do not have a common mother language. JavaScript most certainly does not fit that bill. You could argue C is the lingua franca from the side of the CPU since C runs everywhere, it is literally meant for that. A portable assembly.

C does not run everywhere - you need to compile it to a binary per-platform and per-architecture first, then your platform+arch specific binary only runs on that specific combination... And even then there might be dynamically linked libs to worry about.

You may as well call binary (i.e. 1s and 0s) the Lingua Franca in that case.

Lets not get started on C build chains (especially cross-compiling) ... cmake Vs cygwin Vs msvc Vs whatever else these days with hacky-and-brittle ifdefs conditionals everywhere just to make it work - chaos! JavaScript just runs on pretty much any modern computer you can sit down at or put in your pocket, and even on more exotic things that don't have it installed by default you are about 10 seconds away from installing the official package and you are off and running.

Obviously "Run everywhere" is after compilation. No language works without some kind of processing, and no machine code is not a language. Even if you'd call machine code a language it cannot be called a lingua franca by definition since it's designed to be architecture specific. I'm not sure why you are even start with linked libs, or even linking or libraries at all. That's far removed from the language itself, the C language standard does not prescribe how to link even. It's an implementation detail.