NodeJS - add timeout to a promise

const exec = require("promised-exec")

function onFailure(err) {
    console.log("err", err)
}

function onSuccess(response) {
    console.log("success", response)
}

/**
 * timedPromise(duration)(promise) returns promise that rejects after duration ms
 */
let timedPromise = duration => fx => new Promise((fulfill, reject) => {

    let timer = setTimeout(t => {
        reject("Request took longer than the timeout of " + duration + " ms")
    }, duration)

    let promise = fx.then(response => {
        fulfill(response)
        clearTimeout(timer)
    })
})

timedPromise(1000)(exec("ll"))
    .then(onSuccess)
    .catch(onFailure)