let TestMessage = protobuf.load('./public/protos/message.proto')
    .then((root) => {
        TestMessage = root.lookup('testpackage.TestMessage');
    })

router.get('/', function (req, res, next) {
    const isFinal = Number(req.query.count) >= Math.pow(10, 4);
    const count = isFinal ?
        Number(req.query.count) :
        Math.round(Number(req.query.count) * 1.5);
    const data = crypto.randomBytes(count).toString('hex');
    const msg = TestMessage.encode({
        count,
        data,
        isFinal
    }).finish();

    res.send(msg);
});

import axios from 'axios';
import * as protobuf from 'protobufjs';

const testTextArea = document.querySelector('textarea.test-area');
let TestMessage = protobuf.load('./protos/message.proto')
    .then((root) => {
        TestMessage = root.lookup('testpackage.TestMessage');
    });


function init(count = 1) {
    return axios.get('/data', {
        params: {
            count
        },
        responseType: 'arraybuffer'
    })
        .then((response) => {
            const data = TestMessage.decode(response.data); 
            //TestMessage.decode(new Uint8Array(response.data)); <- works but have stack issues
            testTextArea.innerHTML = data.data;
            if (data.isFinal) { return; }

            return init(data.count);
        });
}