mikowl

// Inspired by https://twitter.com/coderitual/status/1112297299307384833 and https://tapajyoti-bose.medium.com/7-killer-one-liners-in-javascript-33db6798f5bf

//  Remove any duplicates from an array of primitives.
const unique = [...new Set(arr)]

// Sleep in async functions. Use: await sleep(2000).
const sleep = (ms) => (new Promise(resolve => setTimeout(resolve, ms)));
// or
const sleep = util.promisify(setTimeout);

ireade

self.addEventListener('install', (e) => {
    e.waitUntil(
        caches.open("precache").then((cache) => cache.add("/broken.png"))
    );
});

function isImage(fetchRequest) {
    return fetchRequest.method === "GET" && fetchRequest.destination === "image";
}

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent