fetch-bin.js

async () => {

  const response = await fetch('large.bin');
  const buffer = await response.arrayBuffer();

};

json-to-bin.js

const fs = require('fs');

const input = 'large.json';
const output = 'large.bin';


console.log('Reading %s', input);
const buffer = fs.readFileSync(input);

const json = JSON.parse(buffer);

console.log('Writing %s', output);

const outBuffer = new Int8Array(json.data.length);
let index = 0;

for(const item of json.data) {

  // Input is between -1 and 1. This converts that float into a number between
  // 1 and 255 inclusive.
  const newValue = Math.floor((item * 127) + 128);

  outBuffer[index] = newValue; 
  index++;

}

fs.writeFileSync(output, outBuffer);