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jamesknelson /
Last active Oct 3, 2019
Convert a video into a gif

A 4-line shell script to convert your movies into gifs. Defaults to 10fps, 700px wide.

WIDTH=420 FPS=12 togif

You'll need to have ffmpeg installed -- on mac, you can do this with brew:

brew install ffmpeg
View concatStringsAndStreams.js
const CombinedStream = require('combined-stream2');
function concatStringsAndStreams(strings, ...args) {
let combinedStream = CombinedStream.create()
combinedStream.append(Buffer.from(strings[0], 'utf8'))
for (let i = 0; i < args.length; i++) {
let arg = args[i]
let string = strings[i+1]
if (arg && arg.pipe) {

mapObservableToChunkIterator(observable, mapValueToChunks, mapErrorToChunks?): Generator<Promise | Chunk[]>

A function that accepts an Observable with a subscribe() method, and optionally with a getCurrentValue() or getCurrentResult() method.

It returns a Generator that yields Promise (when waiting for a new value) or Chunk objects (i.e. objects that extend { type: string }).

By default, mapErrorToChunks takes the error emitted by an observable, and yields [{ type: 'error', error: error }].

When the observable is complete, the Generator's next() function will return { done: true }.

jamesknelson / component-routing.js
Last active Mar 19, 2019
Two APIs for routing with React that support POST methods and SSR.
View component-routing.js
This component and hook based routing/fetching API won't work, as `useAsync()`
is an impossible component.
In order to use async functions to respond to route changes, the functions will
need to be registered with a parent cache/provider with a unique key. As such, a
more natural component-based architecture would involve a `<Route path>` component
View UpdatePasswordForm.jsx
import { map, redirect, route } from 'navi'
function UpdatePasswordForm({ submitErrors }) {
return (
validate={value =>
value.password !== value.passwordConfirmation &&
View gist:432f00af5522ea07cbb39990a8105e0c
A React app can be split into a number of different types of functions and components, where *each type can depend only on the types above it in the hierarchy*.
This makes gives you a way to split up components and functions over your filesystem. It also helps you to keep components from growing too large, and encourages practices that make testing easier.
types (TypeScript typings)
utils (plain javascript functions)
contexts (React context, and provider components)
jamesknelson /
Last active Aug 22, 2018
React CRUV - 4 directories to solve project structure for good
create-react-app myapp
cd myapp/src
mkdir containers routes utils views
touch config.js contexts.js
mv App.* routes
sed -i '' -e 's/.\/App/.\/routes\/App/g' index.js
View typeof-documentstorage.ts
// typeof DocumentStorage
type DocumentStorage = Batchable<{
willUpdate: false | {
source: boolean | CompoundValueNode<boolean>;
undoHistories: boolean | CompoundValueNode<boolean>;
isAwaitingInitialData: false | {
source: boolean | CompoundValueNode<boolean>;
undoHistories: boolean | CompoundValueNode<boolean>;

I want to make a <TextFieldControl> component that passes a <Description> component to its render function.

Rendering a <Description> would automatically add an id to the element, and then add that id to the aria-describedby prop of the associated input.

For example, this component:

const EmailField = ({ error, value, onChange }) =>
View GovernRedux.js
import * as Govern from 'govern'
* This component subscribes to a Redux store, outputting its current state.
* Typically, you'll use this component as an element in another component's
* `subscribe()` method. For example:
* ```js
* class Identity extends Govern.Component {
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