Problems in passing data from JS to C++

I'm trying to fetch the data from a glb.gz over a http request in JS and want to pass it to c++ file.

**index.js:**
const fetchPromise = fetch("https://xxxserver/text_rendering.glb.gz");
fetchPromise.then(response => {
const data = response.arrayBuffer();//This returns an arrayBuffer.
const bufferData = new Uint8Array(data);
})

**main.cpp:**

char * getBufferData() { return buffer; }

main() {....}

EMSCRIPTEN_BINDINGS(my_module) {
function("getBufferData", &getBufferData);
}

index.html:
var Module = {
preRun: [],
postRun: [],
onRuntimeInitialized: function() {
Module.getBufferData(bufferData));
},

Issues im facing:

1. How to pass the bufferdata in JS file to main.cpp file

2. How to make bufferdata in JS to be visible to index.html for usage in onRuntimeInitialized?

3. I tried the https://emscripten.org/docs/porting/connecting_cpp_and_javascript/embind.html in quick_example.js but the module.lerp function doesnt print any logs. onRuntimeInitialized also doesnt print any logs

Kindly support to help me pass the buffer data from browser to cpp file.