Isomorphic JS, Server-side Rendering, React & Rockefeller

ISOMORPHIC JS, SERVER-SIDE RENDERING, REACT & ROCKEFELLER

• Matthew Dapena-Tretter • matthewwithanm • JavaScript → AS3 → 
Python → JavaScript

• Hirshorn Zuckerman  Design Group • Ofﬁces in Rockville, Baltimore
and NY • ~170 employees  (and growing!) • We ❤ React and ReactDC

• Launched in October of 2014 • One of the
ﬁrst isomorphic React SPAs in production • Our (the?) second • 100s of React components • 7 committers

ISOMORPHIC?

“ISOMORPHIC” • Runs on the server and in the browser
• DRY! • Saves times • Prevents bugs • One language everywhere is good for building a team that can jump around

ISOMORPHIC WHAT? • Routing • Data access • Templating?

BENEFITS OF SSR • Easily read by computers • SEO
• Speed/UX • User doesn’t need to wait for app to  download and initialize • Progressive enhancement makes site  resilient to JS errors

DIFFERENT APPROACHES • Serve rendered HTML → Hydrate → Repeat
• Serve rendered HTML → Hydrate → SPA

hzdg.com JS

hzdg.com JS <html> <head> <title>Welcome | HZDG</title> <meta name=“description” content
<meta name=“keywords” content=“a </head> <body> <div class=“container”> <div>

hzdg.com JS JS <html> <head> <title>Welcome | HZDG</title> <meta name=“description”
content <meta name=“keywords” content=“a </head> <body> <div class=“container”> <div>

hzdg.com JS hzdg.com/contact <html> <head> <title>Contact | HZDG <meta name=“description”
<meta name=“keywords” </head> <body> JS <html> <head> <title>Welcome | HZDG</title> <meta name=“description” content <meta name=“keywords” content=“a </head> <body> <div class=“container”> <div>

<html> <head> <title>Welcome | HZDG</title> <meta name=“description” content <meta name=“keywords”
content=“a </head> <body> <div class=“container”> <div> hzdg.com g JS

<html> <head> <title>Welcome | HZDG</title> <meta name=“description” content <meta name=“keywords”
content=“a </head> <body> <div class=“container”> <div> hzdg.com hzdg.com/contact <html> <head> <title>Contact | HZDG</title> <meta name=“description” content <meta name=“keywords” content=“a </head> <body> <div class=“container”> <div> g JS

WHAT DOES THIS HAVE TO DO WITH REACT? • React
makes it possible • Not a goal of React, just falls out of good functional design • Ember “FastBoot” announced Dec 22

SSR: THE THEORY function myApp(url):DOM

SSR: THE THEORY • One app (function!) generates entire document
• On server: React.renderToString • In browser: React.render

SSR HURDLES: <HEAD> • Not all browsers are cool with
you using innerHTML in head • Different APIs for titles on server and browser • One solution: server-only logic for wrapping UI (and adding head) • Our solution: react-frozenhead

SSR HURDLES: ROUTING

ROUTING SOLUTIONS: REACT-ROUTER-COMPONENT • Features • Declare routes in JSX
• Colocate data requirements with any component via getInitialStateAsync lifecycle method • But… • Fibers? • “React Async is an anti-pattern” • Made server-side integration tricky

ROUTING SOLUTIONS: REACT-ROUTER • Features • Declare routes in JSX
• Based on Ember’s router • But… • No SSR solution in sight—certainly not by our launch date • Looked to be repeating the same mistakes as  react-router-component

ROUTING SOLUTIONS: MONOROUTER • Features • Based on express-style routing
• Designed from the ground up to work with SSR • Generate entire document (including <head>) • But… • Very conservative design • No colocation of data requirements and UI code

UPDATE! REACT-ROUTER • New API announced November 22 • Takes
into account input of Andrey Popp (RRC author) • Colocate data requirements with Handler/Controller components (via convention; e.g. static fetchData) • But… • Lots needs to be done outside of router (data fetching, <head>, …) • …maybe that’s a good thing! • Too late for us…this time

SSR HURDLES: ISOMORPHIC JS • Getting your app to run
in two environments (isomorphic js) • Getting your app to create the same document in both environments

SSR HURDLES: ISOMORPHIC CODE

OUR APPROACH: TWO WEBPACK BUILDS { target: 'node', externals: (
fs.readdirSync(path.resolve('node_modules')) .map((dir) => new RegExp(`^${ dir }(?:$|\/)`)) ), // ... } { target: 'web', // ... }

NODE LIBRARIES • Lots of modules on npm work in
the browser • browserify pioneered “browser”  ﬁeld in package.son • Watch out for: • Packages that access node platform libraries (mostly I/O stuff) • File size!

BROWSER LIBRARIES • $.uhoh • Don’t do browser stuff until
componentDidMount • Watch out for memory leaks on the server • Use webpack’s null-loader to avoid running browser code on the server

DATA ACCESS • Goodbye ORM! • HTTP allthethings.jpg

SSR HURDLES: DETERMINISM

CHECKSUM INVALID?? • Markup generated on server must match DOM
generated in browser • Usually, you’re rendering components with different props • Global state/Flux stores different?

SOURCES OF IMPURITY • Randomness • Temporal values • “3
hours ago” • Date.now() • Stateful external resources (API) • Non-deterministic native APIs • Object iteration • JSON.stringify() • Engine differences

• Circle approximated with two Bézier curves • Drawn using
math (as a function of radius, handle length, stroke width, etc.) for easy tweaking • Animating is just a matter of changing the control points over time

FLOATING POINT MATH! • Who cares about 0.1 + 0.2?!
• 7 / 3 • 2.333333333333334 • 2.3333333333333335

DEALING WITH NON-DETERMINISM • Be on the lookout and avoid!
(toFixed(), etc) • Move code to componentDidMount • only called on client so this is where you can start messing with state with abandon • but nothing you do will be in the initial response (sorry, Google) • so you don’t do much in it • “Fossils”

REHYDRATION & FOSSILS • All state used to generate your
component tree must be the same on the server and in the browser • Most common solution is to serialize state as JSON “fossils” which are used to reconstruct data on the client • Disclaimer: “fossils” is a term we made up

THE FUTURE?

? • Generating the view from the initial request is
limiting • Very little data sent by browsers (viewport size, supported APIs, etc.) and it can’t be inferred from UAs • Maybe we could load bootstrapper and get server-rendered view with an XHR? • Back in hot water with Google (for now).  Use <noscript>? • Is it worth the effort and drawbacks? • Debugging story is still awful (facebook/react#2686) • Google will get there…eventually

THE PRESENT! • The most sane way to develop web
apps so far • Components FTW! • No SEO sacriﬁces • Site feels snappy • Single-language code base • No ugly hacks for Google (like traditional SPAs) • Got a reusable API out of it

HZDG.COM MATTHEWWITHANM MATTHEW DAPENA-TRETTER [email protected] HZDG

Isomorphic JS, Server-side Rendering, React & R...

Isomorphic JS, Server-side Rendering, React & Rockefeller

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