Uber service worker

sw.js

function fetchNCache(e) {
    return fetch(e).then(function(t) {
        if (200 !== t.status)
            return Promise.resolve(t);
        const n = t.clone();
        return caches.open(cacheName).then(function(s) {
            return requestExpectsHtml(e) && !responseIsHtml(n) ? Promise.resolve(t) : void s.put(e.url, n)
        }),
        Promise.resolve(t)
    })
}
function isCacheable(e) {
    return cacheableAssetsPatterns.some(function(t) {
        return t.test(e)
    })
}
function requestExpectsHtml(e) {
    if (!e || !e.headers)
        return !1;
    const t = e.headers.get("Accept");
    return t && t.indexOf("html") > -1
}
function responseIsHtml(e) {
    if (!e || !e.headers)
        return !1;
    const t = e.headers.get("content-type");
    return t && t.indexOf("html") > -1
}
var cacheName = "1498515895721"
  , coreBundleNames = ["https://d3i4yxtzktqr9n.cloudfront.net/lite/javascripts/app-41c1b254320dc7f685f1.js", "https://d3i4yxtzktqr9n.cloudfront.net/lite/javascripts/main-9b6c1b49974ce2e08a47.js", "https://d3i4yxtzktqr9n.cloudfront.net/lite/javascripts/vendor-5f9deee99fb86c0f8f20.js"]
  , cacheableAssetsPatterns = [/^\/$/, /^(\/lite|\/lite-staging\/staging)?\/javascripts\//]
  , HTML_TTL = 2592e5;
self.addEventListener("install", function(e) {
    self.skipWaiting(),
    e.waitUntil(caches.open(cacheName).then(function(e) {
        return e.addAll(coreBundleNames)
    }))
}),
self.addEventListener("activate", function(e) {
    e.waitUntil(caches.keys().then(function(e) {
        return Promise.all(e.map(function(e) {
            if (e !== cacheName)
                return caches["delete"](e)
        }))
    }))
}),
self.addEventListener("fetch", function(e) {
    isCacheable(new URL(e.request.url).pathname) && e.waitUntil(e.respondWith(caches.match(e.request).then(function(t) {
        if (t) {
            if (requestExpectsHtml(e.request)) {
                const n = new Date(t.headers.get("date")).valueOf();
                Date.now() - n > HTML_TTL && fetchNCache(e.request)
            }
            return t
        }
        return fetchNCache(e.request)
    })))
});