workerAsServise.js

function toBlob(func) {
    const funcString = func.toString();
    const code = funcString.substring(
        funcString.indexOf('{') + 1,
        funcString.lastIndexOf('}'),
    );
    const blob = new Blob([code], { type: 'application/javascript' });
    return URL.createObjectURL(blob);
}

function workerFunc() {
    /* eslint-disable no-restricted-globals */
    /* eslint no-unused-vars: ["error", { "varsIgnorePattern": "$" }] */

    function $createRequest({ url, body, method = 'POST' }) {
        const data = {
            method,
            mode: 'cors',
            cache: 'default',
            credentials: 'include',
            body: JSON.stringify(body),
        };
        return fetch(new Request(`https://beta.api.adx1.com/v1.0.2/${url}`, data)).then(
            res =>
                res.text().then(text => {
                    if (res.ok || res.status === 400) {
                        return text;
                    }
                    throw new Error(res.status, res);
                }),
        );
    }

    self.onmessage = e => {
        const { tasks, $models } = JSON.parse(e.data);

        function deSerialazedFunc(string) {
            try {
                /* eslint-disable-next-line no-eval */
                return eval(`(${string})`);
            } catch (error) {
                console.error(error);
                return null;
            }
        }

        const requests = tasks.map(fstr => deSerialazedFunc(fstr));

        requests
            .reduce(
                (prevPromicse, task) =>
                    prevPromicse.then(previosResponse => {
                        if (typeof task === 'function') {
                            return task(previosResponse);
                        }
                        return Promise.resolve(previosResponse);
                    }),
                Promise.resolve(null),
            )
            .then(lastResponse => {
                self.postMessage(lastResponse);
            });
    };
    /* eslint-enable no-restricted-globals */
}

export function createWorker(models, tasks, callBack) {
    const worker = new Worker(toBlob(workerFunc));
    const tasksAsStrings = tasks.map(f => f.toString());
    worker.postMessage(JSON.stringify({ tasks: tasksAsStrings, $models: models }));

    worker.onmessage = e => {
        callBack(e);
    };
    return Promise.resolve();
}