rsms

/* ISC License

Copyright (c) 2020, Rasmus Andersson <rsms.me>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

jed

function tee(asyncIterable) {
  let source = asyncIterable[Symbol.asyncIterator]()

  return [[], []].map((buffer, i, buffers) => ({
    async next() {
      if (0 in buffer) return buffer.shift()

      let item = await source.next()

      if (!item.done) buffers[1 - i].push(item)

pesterhazy

This gist lists challenges you run into when building offline-first applications based on IndexedDB, including open-source libraries like Firebase, pouchdb and AWS amplify (more).

Note that some of the following issues affect only Safari. Out of the major browsers, Chrome's IndexedDB implementation is the best.

Backing file on disk (WAL file) keeps growing (Safari)

When this bug occurs, every time you use the indexeddb, the WAL file grows. Garbage collection doesn't seem to be working, so after a while, you end up with gigabytes of data.

Random exceptions when working with a large number of indexeddb databases (Safari)

jed

// Example usage:
//
// void async function() {
//   let [clicks, onclick] = iterator()
//   document.querySelector('button').addEventListener('click', onclick)
//   for await (let click of clicks) console.log(click)
// }()

export default function iterator() {
  let done = false

rsms

type EventHandler<T=any> = (data :T)=>void

export class EventEmitter<EventMap = {[k:string]:any}> {
  _events = new Map<keyof EventMap,Set<EventHandler>>()

  addListener<K extends keyof EventMap>(e :K, handler :EventHandler<EventMap[K]>) {
    let s = this._events.get(e)
    if (s) {
      s.add(handler)
    } else {

rsms

import { EventEmitter } from "./event"

const print = console.log.bind(console)

const _indexedDB = (window.indexedDB
                 || window["mozIndexedDB"]
                 || window["webkitIndexedDB"]
                 || window["msIndexedDB"]) as IDBFactory

spion

type ExtractValuesRecusrively<T> = T extends FormState<infer U>
  ? { [K in keyof U]: ExtractValuesRecusrively<U[K]> }
  : T extends FieldState<infer V>
  ? V
  : never;

// vs

type ExtractValuesRecusrively<State> = State extends FormState<infer InnerForm>
  ? { [FieldKey in keyof InnerForm]: ExtractValuesRecusrively<InnerForm[FieldKey]> }

rsms

Fixing macOS 10.14, 10.15, 12

Dark main menu without the rest of dark mode

1. Set Light mode
2. defaults write -g NSRequiresAquaSystemAppearance -bool Yes
3. Log out and log back in
4. Set Dark mode

gaearon

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

• Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

jcreedcmu

////////
// The vm module lets you run a string containing javascript code 'in
// a sandbox', where you specify a context of global variables that
// exist for the duration of its execution. This works more or less
// well, and if you're in control of the code that's running, and you
// have a reasonable protocol in mind// for how it expects a certain
// context to exist and interacts with it --- like, maybe a plug-in
// API for a program, with some endpoints defined for it that do
// useful domain-specific things --- your life can go smoothly.