sequential-promise.js

/*export default*/ module.exports = (callbacks, timeout = 0) => {
    callbacks = callbacks.reverse();
    return new Promise((resolve, reject) => {
        const values = [];
        const errors = [];
        let hasError = false;
        (function nextPromise() {
            let currentCallback = callbacks.pop();
            if (currentCallback) {
                currentCallback()
                    .then(value => {
                        values.push(value);
                        errors.push(undefined);
                    })
                    .catch(err => {
                        hasError = true;
                        values.push(undefined);
                        errors.push(err);
                    })
                    .then(() => setTimeout(() => nextPromise(), timeout));
            }
            else if (hasError) {
                reject({ values: values, errors: errors });
            }
            else {
                resolve(values);
            }
        })();
    });
};