Olov Sundström coolov

What is Relay?

Relay is a new framework from Facebook that provides data-fetching functionality for React applications. It was announced at React.js Conf (January 2015).

Hi Nicholas,

I saw you tweet about JSX yesterday. It seemed like the discussion devolved pretty quickly but I wanted to share our experience over the last year. I understand your concerns. I've made similar remarks about JSX. When we started using it Planning Center, I led the charge to write React without it. I don't imagine I'd have much to say that you haven't considered but, if it's helpful, here's a pattern that changed my opinion:

The idea that "React is the V in MVC" is disingenuous. It's a good pitch but, for many of us, it feels like in invitation to repeat our history of coupled views. In practice, React is the V and the C. Dan Abramov describes the division as Smart and Dumb Components. At our office, we call them stateless and container components (view-controllers if we're Flux). The idea is pretty simple: components can't

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

Service Worker - offline support for the web

Progressive apps - high-res icon, splash screen, no URL bar, etc.

Progressive Web Apps: Escaping Tabs Without Losing Our Soul

Problem: How can we preprocess JavaScript (at build-time or on the server-side) so engines like V8 don't have to spend as much time in Parse? This is a topic that involves generating either bytecode or a bytecode-like-abstraction that an engine would need to accept. For folks that don't know, modern web apps typically spend a lot longer in Parsing & Compiling JS than you may think.

Yoav: This can particularly be an issue on mobile. Same files getting parsed all the time for users. Theoretically if we moved the parsing work to the server-side, we would have to worry about it less.
One angle to this problem is we all ship too much JavaScript. That's one perspective. We could also look at preprocessing.
We've been talking about this topic over the last few weeks a bit with V8. There were three main options proposed.
1. Similar to what optimize-js does. Identify IIFEs and mark them as such so the browser and VMs heuristics will catch them and do a better job than today. optimize-js only tackles IIFE bu

	(ns ical.core
	(:require
	[om.core :as om :include-macros true]
	[om.dom :as dom :include-macros true]
	[sablono.core :as html :refer-macros [html]]))

	(enable-console-print!)

	(def weekdays ["saturday" "monday" "tuesday" "wednesday" "thursday" "friday" "sunday"])

	System.config({
	baseURL: "/",
	defaultJSExtensions: true,
	transpiler: "babel",
	babelOptions: {
	"optional": [
	"runtime",
	"optimisation.modules.system"
	]
	},

	/**
	* @author mrdoob / http://mrdoob.com/
	*/

	function html2canvas( element ) {

	var range = document.createRange();

	function getRect( rect ) {

	function bar(func) {
	console.log('bar entered');
	func(5);
	console.log('bar exiting');
	}

	function foo() {
	var x = callCC(function(cont) {
	console.log('calling bar');
	bar(cont);

Olov Sundström coolov

Contents

What is Relay?

What forces layout / reflow

Element APIs

Getting box metrics