At first, you might hope that just calls the function and let it tell you just when the job is done and you wait … and wait. Soon, you realize that the callback you have been waiting will never come.

This is true, and I can pretty much guarantee you that. I have been working with a project involves in heavy IO operations. Even I try to fine tune the speed at which node reads. It is not suffice as I have seen. It soon slows down and stops completely with the cause I have yet to find.

So, I decided that I have to put some timeout, which is not provided by default means, here is my attempt:

export async function delay(ms: number) {
    return new Promise<void>((res, rej) => {
        setTimeout(() => res(), ms)

class Timeout extends Error {}
export async function delayedError(timeout: number) {
    await delay(timeout)
    throw new Timeout()

export async function withTimeout<T>(promise: Promise<T>, timeout: number) {
    return await Promise.race<T>([
        delayedError(timeout) as any

Let’s further say that wrap the fs.readFile with this async:

import fs = require('fs')

export async function readFile(path: string) {
    return new Promise<Buffer>((res, rej) => {
        fs.readFile(path, (err, content) => {
            if (err) rej(err)
            else res(content)

To use it, now you can:

try {
    await withTimeout(readFile('test.txt'), 1000)
} catch (err) {
    if (err instanceof Timeout) {
    } else {
        throw err