Christopher Patty chrisjpatty

The blog post has been written: https://kentcdodds.com/blog/typescript-function-syntaxes

TypeScript Function Syntaxes

I'm trying to create examples of all the different ways to write functions and function type definitions in TypeScript.

One requirement is these examples must work with strict mode (noImplicitAny, etc) enabled.

If I'm missing anything, please add comments below with examples. I'll eventually put this into a blog post.

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.

Redux Selector Pattern

Imagine we have a reducer to control a list of items:

function listOfItems(state: Array<Object> = [], action: Object = {}): Array<Object> {
  switch(action.type) {
    case 'SHOW_ALL_ITEMS':
      return action.data.items
    default:

	import * as React from 'react'
	import { SpringValue, easings, useSpring } from 'react-spring'

	/**
	* Hook that animates height when args.animationKey changes
	*
	* Ex:
	* const animatedBlock = useAnimatedHeight({
	* animationKey: key,
	* })

	#!/bin/bash

	DAYS_SINCE_LAST_CHANGE=14 # If a project hasn't been touched in this long its node_modules will be deleted
	SEARCH_PATH="./Git" # Update this to the path where your code is stored

	TOTAL_BYTES_REMOVED=0
	Mb=1000000
	Kb=1000

	node_modules=$(find $SEARCH_PATH -name "node_modules" -type d -prune)

	# Playback on USB audio device (the second soundcard's first device),
	# with omxplayer:
	#
	# $ ./play.sh myfile.mp4
	#
	# Use 'aplay -l' to list available devices, e.g:
	#
	# $ aplay -l
	# card 1: Device [USB Audio Device], device 0: USB Audio [USB Audio]
	# Subdevices: 1/1

	{
	"vars": {
	"@gray-base": "#000",
	"@gray-darker": "lighten(@gray-base, 13.5%)",
	"@gray-dark": "lighten(@gray-base, 20%)",
	"@gray": "lighten(@gray-base, 33.5%)",
	"@gray-light": "lighten(@gray-base, 46.7%)",
	"@gray-lighter": "lighten(@gray-base, 93.5%)",
	"@brand-primary": "rgb(41, 41, 105)",
	"@brand-success": "rgb(66, 173, 66)",

	var fs = require('fs'),
	request = require('request');
	src = require('./dataset.js'); //external array with url of images that need to be downloaded

	var download = function(uri, filename, callback){

	request.head({url:uri, followAllRedirects: true}, function(err, res, body){

	console.log('content-type:', res.headers['content-type']);
	console.log('content-length:', res.headers['content-length']);

	pico-8 cartridge // http://www.pico-8.com
	version 4
	__lua__
	player = {}
	player.x = 5
	player.y = 5
	player.sprite = 0
	player.speed = 2

	function move()