Javascript Array forEachSerial = async function(fn)

export function serial(tasks, fn) {
    return tasks.reduce((promise, task) => promise.then(previous => fn(task, previous)), Promise.resolve(null))
}

export function parallel(tasks, fn) {
    return Promise.all(tasks.map(task => fn(task)))
}

Array.prototype.forEachSerial = async function(fn) {
    return serial(this, fn);
}

Array.prototype.forEachParallel = async function(fn) {
    return parallel(this, fn);
}