karol-majewski

import { AnyAction, Reducer } from 'redux';

/**
 * Equivalent for `handleActions` from the redux-actions` library.
 * @see https://redux.js.org/recipes/reducing-boilerplate#generating-reducers
 *
 * @template T Reducer shape.
 */
export function createReducer<T>(handlers: Record<string, Reducer<T>>, initialState: T): Reducer<T> {
  return (state: T = initialState, action: AnyAction): T => {

karol-majewski

/**
 * TypeScript version of @istarkov's cancellable Promise wrapper.
 *
 * @see https://github.com/facebook/react/issues/5465#issuecomment-157888325
 */
const makeCancelable = <T>(promise: Promise<T>): { promise: Promise<T>; cancel(): void } => {
  let hasCanceled = false;

  const wrappedPromise = new Promise<T>((resolve, reject) => {
    promise.then(

karol-majewski

export function flatMap<T, U>(array: T[], callbackfn: (value: T, index: number, array: T[]) => U[]): U[] {
  return Array.prototype.concat(...array.map(callbackfn));
}

karol-majewski

import { AnyAction, Middleware } from 'redux';

export const userTimingMiddleware: Middleware = () => {
  return next => {
    return <A extends AnyAction>(action: A): A => {
      if (performance.mark === undefined) {
        return next(action);
      }

      performance.mark(`${action.type}_start`);

karol-majewski

Applying default values

If our dependencies look like this:

declare class Repository<T> {
  find<T>(options: FindOptions): Promise<T>;
}

interface FindOptions {

karol-majewski

enum PokemonType {
    Water,
    Rock,
    Fire,
    Air,
    Electric,
    Poison
}

class Pokemon {

karol-majewski

/**
 * TypeScript version of the solution proposed by @kitze.
 * 
 * @see https://gist.github.com/kitze/23d82bb9eb0baabfd03a6a720b1d637f
 */
import React from 'react';

interface Props<T = {}> {
  condition: boolean;
  render: (children: React.ReactElement<T> | null) => React.ReactElement<T> | null;

karol-majewski

type IdentityFunction<T> = (argument: T) => T;

type InnerHTMLTransformer = IdentityFunction<string>;

type RegularExpressionFlags =
  | 'i'
  | 'g'
  | 'ig';

type Phrase = string | RegExp;

karol-majewski

/node_modules/
webpack:///webpack
^webpack://.*/process\-update\.js$
^webpack://.*/client\.js$
^debugger://
\(webpack\)-hot-middleware
webpack/bootstrap
/jquery\.min\.js$
/jquery\-migrate\-1\.4\.1\.min\.js$

karol-majewski

{
  "compilerOptions": {
    /* Basic Options */
    "target": "es2015",                       /* Specify ECMAScript target version: 'ES3' (default), 'ES5', 'ES2015', 'ES2016', 'ES2017','ES2018' or 'ESNEXT'. */
    "module": "esnext",                       /* Specify module code generation: 'none', 'commonjs', 'amd', 'system', 'umd', 'es2015', or 'ESNext'. */
    "lib": [                                  /* Specify library files to be included in the compilation. */
      "dom",
      "esnext"
    ],
    // "allowJs": true,                       /* Allow javascript files to be compiled. */