How to understand relationship between wasm file and wasi js file

Questions
#1

I’m learning how to use call tvm using javascript under the web sub-directory. When reading the following two examples:

  1. web/tests/node/test_packed_func.js
const EmccWASI = require(path.join(wasmPath, "tvmjs_runtime.wasi.js"));
const wasmSource = fs.readFileSync(path.join(wasmPath, "tvmjs_runtime.wasm"));

let tvm = new tvmjs.Instance(
  new WebAssembly.Module(wasmSource),
  new EmccWASI()
);
  1. web/tests/node/test_module_load.js
const EmccWASI = require(path.join(wasmPath, "tvmjs_runtime.wasi.js"));
const wasmSource = fs.readFileSync(path.join(wasmPath, "test_addone.wasm"));

const tvm = new tvmjs.Instance(
  new WebAssembly.Module(wasmSource),
  new EmccWASI()
);

From the makefile, *.cc → *.bc → tvmjs_runtime.wasm → tvmjs_runtime.js → tvmjs_runtime.wasi.js .

In my think, the tvmjs_runtime.wasm is needed by all example (PackedFunc, Module implement in this wasm file). But when look at the second example, the tvmjs_runtime.wasm not loaded, that confused me – where’s the TVM functionality come from? If tvmjs_runtime.wasm is not necessary, why it is loaded in the fist example.