Some Cool Nuggets

useMatchMutate

A custom hook to revalidate multiple queries in SWR using regular expressions with. Thanks Lazar for this ✨

import { useSWRConfig } from "swr";

export function useMatchMutate() {
    const { cache, mutate } = useSWRConfig();
    return (matcher, ...args) => {
        if (!(cache instanceof Map)) {
            throw new Error(
                "matchMutate requires the cache provider to be a Map instance",
            );
        }

        const keys = [];

        for (const key of cache.keys()) {
            if (matcher.test(key)) {
                keys.push(key);
            }
        }

        const mutations = keys.map((key) => mutate(key, ...args));
        return Promise.all(mutations);
    };
}

keyExtractor

Part of my advanced TypeScript learning, extracting keys from an object array using Generics. This really improves the developer experience when I write my own utilities ✨

function keyExtractor<Data, Key extends keyof Data>
(data: Data[], key: Key) => return data.map(el => el[key]);

formatToMilitary

I've found myself in this dilemma of converting a number and it's meridiem to a proper 24 hour time when generate ISO timestamps. Simple, yet convenient ✨

function formatToMilitary(hour: number, meridiem: string) {
  if (meridiem === "AM") {
    if (hour === 12) return 0;
    return hour;
  } else {
    if (hour === 12) return 12;
    return hour + 12;
  }
}