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jpkempf / gist.ts
Last active January 5, 2021 09:55
Using TypeScript function overloads and generics to narrow down return types
/**
* interactive playground link:
* https://www.typescriptlang.org/play?#code/C4TwDgpgBAwg9gWzAQwHYgAoCcIDMI6oDGEAzlALxQDeAUFFMmGFnAG7IA2AXDfQ1GAALHKSFxOAE150BAgKIBVAEq9UAVwQAjAgG5+DAL76jJqDgDmAS1LAsyYFbioZBqFdRsrwCLy1wJCDQzBlIITlw-AM4g1BCoAHchb3CbYF5bLA8LM2NaPNpQSChsPAIIYggAaQgQSigAa1q4XFhEFHRS-EISUn1aAHoBqFx1YkdnKHYCTjhkSXIuWYSoABUAZUE4KFRkLFYVyTgE1EEhaBxgdSxToogAOkHhokQECuAp9Q-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
@jpkempf
jpkempf / extract.ts
Created April 23, 2021 15:18
TypeScript magic with Extract
// source: https://twitter.com/mpocock1/status/1385610014639988739
const fields = [{
inputType: 'text',
label: 'ID',
name: 'id'
}, {
inputType: 'text',
label: 'Description',
name: 'description'
@jpkempf
jpkempf / useMockPerformanceObserver.ts
Created February 7, 2022 15:27
Custom Hook to mock the PerformanceObserver API
import { useEffect } from 'react';
const useMockPerformanceObserver = (): void => {
useEffect(() => {
const OriginalPerformanceObserver = window.PerformanceObserver;
class MockPerformanceObserver extends PerformanceObserver {
disconnect = () => null;
observe = () => null;
@jpkempf
jpkempf / fetchers.ts
Last active June 26, 2023 16:26
Helper to create fully typed fetcher functions with built-in error handling
/**
* This function returns a new function that handles HTTP calls, logging, and errors.
* It is meant for API route helpers but could be used for other kinds of calls as well.
*
* @param name the name of the new function; used for logging
* @param fetcher the function that makes the HTTP call
* @returns a new function that calls the fetcher and handles errors and logging
*/
const createFetcher =
@jpkempf
jpkempf / HOC.ts
Created January 30, 2024 15:52 — forked from vezaynk/HOC.ts
HOC helpers. reduceHOCs and applyHOCs.
interface HOC<T> {
(Component: React.ComponentType<T>): (props: T) => JSX.Element
}
const reduceHOCs = <T>(...hocs: HOC<T>[]): HOC<T> => hocs
.reduce((reduced, next) => (c) => next(reduced(c)));
const applyHOCs = <T>(...hocs: HOC<T>[]) {
const reducedHoc = reduceHOCs(...hocs);