Async sleep — return a promise that waits for ms

sleep.ts

/**
 * Sleeps for `ms` milliseconds.
 * @param {number} ms
 * @return {Promise}
 */
async function sleep (ms:number) {
    await new Promise((resolve) => {
        if (!ms) {
            process.nextTick(resolve)
        } else {
            setTimeout(resolve, ms)
        }
    })
}