Intro til ReactJS

for C# udviklere

Ditmer Academy 2016

(Use touchdevice or arrowkeys to navigate)

  1. Hvad? (Hvad er ReactJS?)
  2. Hvorfor? (Hvorfor bruge ReactJS?)
  3. Hvordan? (Hvordan kommer man igang?)
    • Shaving the Yak
    • Avoid shaving the Yak
    • Vis mig nu bare koden!
  4. Licens - issue?
  5. What's next?
    • ReactFiber, ReactNative


Et JavaScript bibliotek til at skabe UI

Det beskrives ofte som V'et i MVC

Data-first paradigm

(That's not a thing!?)

Data er state er data er state

DOM first > Data-first

Vi modificerer ikke DOM'en, vi modificerer data og DOM'en følger (magisk) med.

Data-first paradigm


var configDiv = "div[class=group]:last"; $(configDiv).find('div').first().html(addTab(index, sortIndex));


configurations.push(defaultConfig()); this.setState({model : configurations });

Hvorfor bruge ReactJS. Top 3 grunde.

1. Fast

2. Fast


Andre grunde til at bruge ReactJS

Benyt den CPU power/RAM der er i klienten

Det er let at gemme vores frontend state og genskabe den.

New and exciting

Fordele / ulemper


JavaScript / JSX / ReactJS er kun et viewlag


JavaScript / JSX / ReactJS er kun et viewlag

JavaScript development explained:

Editor: Atom

Udviklet af GitHub

Bygget helt i JavaScript (Electron

Forstår ReactJS JSX syntax, inkl. code completion

Editor: Visual Studio Code

Udviklet af Microsoft

Free. Open source. Runs everywhere.

Forstår ReactJS JSX syntax, inkl. code completion

Hvorfor overhovedet bruge Atom eller Code?

Hvorfor have en ekstra editor ved siden af VS

Hvorfor sætte sig ind i en ny IDE

Traditionel webapp (f.eks. MVC + JQuery)

ReactJS - Virtual DOM

Re-render alt (in-memory) hver gang data ændre sig:

  1. "Data-first" tankegang
  2. Declarative beskrivelse af UI flow
  3. En helt ny app renderes i memory
  4. Det mindste sæt af ændringer beregnes og pushes til DOM'en

Virtual DOM fordele

  1. Mere læsbar kode
    Det er tydeligt hvad hver komponent gør
  2. Hurtigt
    Skrivning til DOM'en håndteres af ReactJS


Thinking in React

Thinking in React

Thinking in React

Data / State

var model = { masterdata: { "weeks": [{ "description": "Uge 7 (ons-lør)", "key": 925 }, { "description": "Uge 8 (ons-lør)", "key": 926 }], "countries": [{ "name": "Denmark", "key": 1, "currency": "DKK", "rate": 7.4356 }, { "name": "Sweden", "key": 2, "currency": "SEK", "rate": 9.5849 }, { "name": "Norway", "key": 3, "currency": "NOK", "rate": 9.2609 }], "selectedCountry": 1 }, "route": { "description": "CPH-SZG (SK7881) - SZG-CPH (SK7882)", "key": 314, "destinations": [{ "name": "Bad Gastein", "key": 423, "hotels": [{ "name": "Hotel Elisabethpark", "key": 962, "open": true, "roomTypes": [{ "description": "Dobbeltværelse u. dusch/wc m. opredning", "key": 443, "discounts": [{ "week": 925, "key": 2342, "units": 2, "price": 1000, "discount": 0 }, { "week": 926, "key": 2343, "units": 1, "price": 1100, "discount": 0 }] }, { "description": "Dobbeltværelse m. dusch/wc", "key": 343, "discounts": [{ "week": 925, "key": 2344, "units": 0, "price": 1300, "discount": 0 }, { "week": 926, "key": 2345, "units": 1, "price": 1300, "discount": 0 }] }] }......



<div onClick={this.handleClick}> Hello {}, welcome to the system. Click here. </div>


HelloWorld.jsx: <div onClick={this.handleClick}> <Greeting name={}/> Click here. </div>
Greeting.jsx: <span> Hello {}, welcome to the system. </span>



var actions = { update_country: function update_country(countryKey) { self.state.model.masterdata.selectedCountry = countryKey; self.setState({ model: self.state.model }); }

Passing actions to your components

<MyComponent mydataset={someobj.dataset} myactions={actions}/> this.props.myactions.update_country(;

Shaving the Yak

"Any apparently useless activity which, by allowing you to overcome intermediate difficulties, allows you to solve a larger problem."

Shaving the Yak

Shaving the Yak

Avoid shaving the Yak


<script src=""></script> <script src=""></script> <div id="helloApp"></div> <script src="./scripts/HelloWorld.jsx"></script>

"The files will automatically be compiled to JavaScript and cached server-side. No precompilation required. Perfect for development."


var HelloWorld = React.createClass({ render: function() { return <div>Hello world!</div>; } }) ReactDOM.render( <HelloWorld />, document.getElementById('helloApp') );

Hvordan kan man kalde .jsx scripts direkte?

Web.config: <httpHandlers> <add verb="GET" path="*.jsx" type="React.Web.BabelHandlerFactory, React.Web" /> </httpHandlers>

Mindre tweak...

.\App_Start\ReactConfig.cs: public static class ReactConfig { public static void Configure() { ReactSiteConfiguration.Configuration.SetReuseJavaScriptEngines(false); } };


// In BundleConfig.cs bundles.Add(new JsxBundle("~/bundles/main").Include( // Add your JSX files here "~/Scripts/HelloWorld.jsx", "~/Scripts/AnythingElse.jsx", // You can include regular JavaScript files in the bundle too "~/Scripts/ajax.js", ));
<!-- In your view --> @Scripts.Render("~/bundles/main")

Bundle - for production

Ulemper ved at bruge React.NET

Ingen support for JavaScript Modules
import { Provider } from 'react-redux'; Ingen compile/transpile fejlbeskeder
SyntaxError: ./ReactYak/source/hello.jsx: Unexpected token, expected } (6:63) 4 | class Hello extends React.Component { 5 | render() { > 6 | return <h1 style={{color:'grey'}}>Hello {;}</h1> | ^ 7 | 8 | } 9 | }

Licens. Do you agree....

Yes yes yes - next next next

Additional Grant of Patent Rights Version 2
"Software" means the React software distributed by Facebook, Inc.

Facebook, Inc. ("Facebook") hereby grants to each recipient of the Software ("you") a perpetual, worldwide, royalty-free, non-exclusive, irrevocable (subject to the termination provision below) license under any Necessary Claims, to make, have made, use, sell, offer to sell, import, and otherwise transfer the Software. For avoidance of doubt, no license is granted under Facebook's rights in any patent claims that are infringed by (i) modifications to the Software made by you or any third party or (ii) the Software in combination with any software or other technology.

The license granted hereunder will terminate, automatically and without notice, if you (or any of your subsidiaries, corporate affiliates or agents) initiate directly or indirectly, or take a direct financial interest in, any Patent Assertion: (i) against Facebook or any of its subsidiaries or corporate affiliates, (ii) against any party if such Patent Assertion arises in whole or in part from any software, technology, product or service of Facebook or any of its subsidiaries or corporate affiliates, or (iii) against any party relating to the Software. Notwithstanding the foregoing, if Facebook or any of its subsidiaries or corporate affiliates files a lawsuit alleging patent infringement against you in the first instance, and you respond by filing a patent infringement counterclaim in that lawsuit against that party that is unrelated to the Software, the license granted hereunder will not terminate under section (i) of this paragraph due to such counterclaim.

A "Necessary Claim" is a claim of a patent owned by Facebook that is necessarily infringed by the Software standing alone.
A "Patent Assertion" is any lawsuit or other action alleging direct, indirect, or contributory infringement or inducement to infringe any patent, including a cross-claim or counterclaim.

Kort sagt:

Facebook, Inc. hereby grants you irrevocable license - subject to the termination provision below

The license granted hereunder will terminate [if your product takes] a direct financial interest in, any Patent Assertion: (i) against Facebook or any of its subsidiaries or corporate affiliates

"Du må ikke, lave noget der konkurerer med facebook eller sagsøge facebook for patentbrud."

"De siger på nettet..."

This is the reason why both Google and Microsoft employees are not allowed to use React.js in their work - according to Rob Eisenberg, creator of the Aurelia framework and a former member of the Angular 2 development team. - Written by Jorgé on Saturday July 16, 2016

Er det så slemt?

Arnt Schøning

Office Delve

til Office 365 og SharePoint

Arnt Schøning - Tweet

Office Delve

What's next for ReactJS?

React Fiber

React Fiber is an ongoing reimplementation of React's core algorithm. It is the culmination of over two years of research by the React team.

The goal of React Fiber is to increase its suitability for areas like animation, layout, and gestures. Its headline feature is incremental rendering: the ability to split rendering work into chunks and spread it out over multiple frames.

Other key features include the ability to pause, abort, or reuse work as new updates come in; the ability to assign priority to different types of updates; and new concurrency primitives.

What's next for React Developers

Mere info: