sebmarkbage

I heard some points of criticism to how React deals with reactivity and it's focus on "purity". It's interesting because there are really two approaches evolving. There's a mutable + change tracking approach and there's an immutability + referential equality testing approach. It's difficult to mix and match them when you build new features on top. So that's why React has been pushing a bit harder on immutability lately to be able to build on top of it. Both have various tradeoffs but others are doing good research in other areas, so we've decided to focus on this direction and see where it leads us.

I did want to address a few points that I didn't see get enough consideration around the tradeoffs. So here's a small brain dump.

"Compiled output results in smaller apps" - E.g. Svelte apps start smaller but the compiler output is 3-4x larger per component than the equivalent VDOM approach. This is mostly due to the code that is usually shared in the VDOM "VM" needs to be inlined into each component. The tr

mikaello

Group array of JavaScript objects by keys

This fork of JamieMason's implementation changes the key parameter to be an array of keys instead of just a single key. This makes it possible to group by multiple properties instead of just one.

Implementation

const groupBy = keys => array =>
  array.reduce((objectsByKeyValue, obj) => {
    const value = keys.map(key => obj[key]).join('-');

saionaro

//...
// some interfaces imports skipped
//...

const createDirectUploadMutation = `
  mutation createDirectUploadMutation(
    $filename: String!
    $byteSize: Int!
    $contentType: String!
  ) {

killants

/**
 * searches deep into an object recursively...
 * @param {Object} obj object to be searched
 * @param {any} searchValue the value/key to search for
 * @param {Object} [options]
 * @param {boolean} options.[searchKeys] whether to search object keys as well as values. Defaults to `true` if `serchValue` is a string, `false` otherwise.
 * @param {number} options.[maxDepth=20] maximum recursion depth (to avoid "Maximum call stack size exceeded")
 * @returns {string[]} Paths on the object to the matching results
 */
const findPaths = (

kentcdodds

// NOTE: you will NOT write code like this when using suspense
// instead, you'll use react-cache (not yet officially published)
// it'll handle things like pre-loading, handling rapid re-renders, etc.

const cache = {}

function FetchPokemon({pokemonName}) {
  const pokemon = cache[pokemonName]
  if (!pokemon) {
    const promise = fetchPokemon(pokemonName).then(

bvaughn

This API was removed in React 17

---

Interaction tracing with React

React recently introduced an experimental profiler API. After discussing this API with several teams at Facebook, one common piece of feedback was that the performance information would be more useful if it could be associated with the events that caused the application to render (e.g. button click, XHR response). Tracing these events (or "interactions") would enable more powerful tooling to be built around the timing information, capable of answering questions like "What caused this really slow commit?" or "How long does it typically take for this interaction to update the DOM?".

With version 16.4.3, React added experimental support for this tracing by way of a new NPM package, scheduler. However the public API for this package is not yet finalized and will likely change with upcoming minor releases, so it should be used with caution.

bbugh

import { ApolloClient } from 'apollo-client'
import { split } from 'apollo-link'
import { HttpLink } from 'apollo-link-http'
import { InMemoryCache } from 'apollo-cache-inmemory'
import { getMainDefinition } from 'apollo-utilities'
import { createPersistedQueryLink } from 'apollo-link-persisted-queries'
import { setContext } from 'apollo-link-context'

// AC: IMPORT ACTIONCABLE
import ActionCable from 'actioncable' 

phusick

{
  "breakpoints": {
    "keys": [
      "xs",
      "sm",
      "md",
      "lg",
      "xl"
    ],
    "values": {

sebmarkbage

The Rules of React

All libraries have subtle rules that you have to follow for them to work well. Often these are implied and undocumented rules that you have to learn as you go. This is an attempt to document the rules of React renders. Ideally a type system could enforce it.

What Functions Are "Pure"?

A number of methods in React are assumed to be "pure".

On classes that's the constructor, getDerivedStateFromProps, shouldComponentUpdate and render.

dinatih

# config/initializers/activestorage.rb
Rails.application.config.to_prepare do
  # Provides the class-level DSL for declaring that an Active Record model has attached blobs.
  ActiveStorage::Attached::Macros.module_eval do
    def has_one_attached(name, dependent: :purge_later, acl: :private)
      class_eval <<-CODE, __FILE__, __LINE__ + 1
        def #{name}
          @active_storage_attached_#{name} ||= ActiveStorage::Attached::One.new("#{name}", self, dependent: #{dependent == :purge_later ? ":purge_later" : "false"}, acl: "#{acl}")
        end