Eric Chernuka ericchernuka

So you want to write a sync system for a web app with offline and realtime support? Good luck. You might find the following resources useful.

Overview articles

Database in a browser, a spec (Stepan Parunashvili)

What problem are we trying to solve with a sync system?
The web of tomorrow (Nikita Prokopov)

auth0-react static getAccessToken method

There are many use cases to use getAccessTokenSilently outside of a component (for example, in an Axios Interceptor or an Apollo Client).

It's tempting to ask for the option to pass an Auth0Client instance into the Auth0Provider so that its getTokenSilently method can used outside of the context of a component, eg.

const client = new Auth0Client();
export const getAccessToken = () => client.getTokenSilently();

Exclude node_modules and .git from Backblaze backups on Mac

Edit the file at /Library/Backblaze.bzpkg/bzdata/bzexcluderules_editable.xml.
Add these rules inside the bzexclusions tag:

<!-- Exclude node_modules. -->
<excludefname_rule plat="mac" osVers="*"  ruleIsOptional="t" skipFirstCharThenStartsWith="users/" contains_1="/node_modules/" contains_2="*" doesNotContain="*" endsWith="*" hasFileExtension="*" />
<excludefname_rule plat="mac" osVers="*"  ruleIsOptional="t" skipFirstCharThenStartsWith="users/" contains_1="/.git/" contains_2="*" doesNotContain="*" endsWith="*" hasFileExtension="*" />

3 Gripes With React

I started using React 3.5 years ago, and I still love it. It was such a well-designed solution that not much has changed since then, only superficial stuff like naming. What I learned then is still wholly applicable today because it's such a good idea (although now you can choose from many other libraries). On top of that, we now benefit from an entirely new architecture (fiber) without changing much.

	// TODO: make `pages` optional and measure the div when unspecified, this will
	// allow more normal document flow and make it easier to do both mobile and
	// desktop.
	import {
	createContext,
	useCallback,
	useContext,
	useEffect,
	useMemo,
	useRef,


	// when T is any\|unknown, Y is returned, otherwise N
	type IsAnyUnknown<T, Y, N> = unknown extends T ? Y : N;

	// when T is never, Y is returned, otherwise N
	type IsNever<T, Y = true, N = false> = [T] extends [never] ? Y : N;

	// when T is a tuple, Y is returned, otherwise N
	// valid tuples = [string], [string, boolean],
	// invalid tuples = [], string[], (string \| number)[]

	import { setIn } from 'final-form';
	import { useMemo } from 'react';

	/**
	* Sets the `innerError.message` in an `errors` object at the key
	* defined by `innerError.path`.
	* @param {Object} errors The object to set the error in.
	* @param {{ path: string, message: string }} innerError A `yup` field error.
	* @returns {Object} The result of setting the new error message onto `errors`.
	*/

	import * as yup from 'yup';
	import { setIn } from 'final-form';

	const validationSchema = yup.object({
	email: yup.string().email(),
	shipping: yup.object({
	name: yup.string(),
	phone: yup.object({
	code: yup.string().matches(/^\+\d+$/i),
	number: yup.number().max(10),

	import { omit } from 'lodash';

	const filter = () => true;
	const getUndefined = () => {};
	const getType = (action) => action.type;
	const identity = (x) => x;

	const createSentryMiddleware = (Sentry, options = {}) => {
	const {
	actionTransformer = identity,

	import PropTypes from 'prop-types';

	type Omit<T, K> = Pick<T, Exclude<keyof T, K>>;

	type Defined<T> = T extends undefined ? never : T;

	/**
	* Get the type that represents the props with the defaultProps included.
	*
	* Alternatively, we could have done something like this: