JSON запрос

const https = require('https');
const querystring = require('querystring');

const TOKEN = process.env.TOKEN || '5dce19710a5e26ab8b7b8986cb3c49e58C291791B7F0A7AEB8AFBFCEED7DC03BC48FF5F8';

doLogin();

function doLogin() {
    doApiRequest('token/login', {
        params: {
            token: TOKEN,
            fl: 1,
        },
    }, (error, data) => {
        if (error) { console.error(error); return; }
        if (!data || data.error || !data.eid) { console.error(data); return; }

        fetchItems({ sid: data.eid });
    });
}

function fetchItems({ sid }) {
    doApiRequest('core/search_items', {
        sid,
        params: {
            spec: {
                itemsType: 'avl_unit',
                propName: 'sys_id',
                propValueMask: '*',
                sortType: 'sys_id'
            },
            force: 1,
            flags: 1 | 0x100 | 0x400000,
            from: 0,
            to: 0,
        },
    }, (error, data) => {
        if (error) { console.error(error); return; }
        if (!data || data.error) { console.error(data); return; }

        console.log(data);

        logout({ sid });
    });
}

function logout({ sid }) {
    doApiRequest('core/logout', {
        sid,
        params: {},
    });
}

function doApiRequest(svc, { sid, params }, callback) {
    let req = https.request({
        hostname: 'hst-api.wialon.com',
        path: '/wialon/ajax.html?svc=' + svc + (sid ? '&sid=' + sid : ''),
        method: 'POST',
        headers: {
            'Content-Type': 'application/x-www-form-urlencoded',
        },
    }, res => {
        let buffers = [];
        let totalLength = 0;

        res.on('error', error => {
            if (callback) { callback(error); callback = null; }
        });

        res.on('data', buffer => {
            buffers.push(buffer);
            totalLength += buffer.length;
        });

        res.on('end', () => {
            let totalBuffer = Buffer.allocUnsafe(totalLength);

            let offset = 0;
            buffers.forEach(buffer => {
                buffer.copy(totalBuffer, offset);
                offset += buffer.length;
            });

            let json = JSON.parse(totalBuffer.toString('utf8'));

            if (callback) { callback(null, json); callback = null; }
        });
    });

    req.end(querystring.stringify({ params: JSON.stringify(params) }));
}