async readbody of a http request

read-body.js

function readBody(req) {
    return new Promise((resolve, reject) => {
        let body = "";
        req.on("data", (chunk) => { body += "" + chunk; });
        req.on("end", () => { resolve(body); });
        req.on("error", (err) => { reject(err); });
    });
}