Angular 2 Overview

Alexander Shevnin, JSC “Arcadia Inc.”

About myself

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Alexander ShevninJSC “Arcadia Inc.”

alexander.shevnin@arcadia.spb.ru

In Arcadia from 2012, last 3 years work mostly with ASP.NET, C#, AngularJS and TypeScript

Intro

• New major version of Angular framework from Google

• Single Page Applications

• Built from scratch

• Written on Typescript

• Can run in web worker or server-side

• Npm packages: @angular/*

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Topics for today:

• Core concepts

• A bit about Reactive programming

• What do I need to use it today (dependencies, browser compatibility and so on)?

• JIT vs AOT (brief look at compilation)

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This is NOT about:

• Copying api-documentation

• Comparison with other libraries / frameworks (save for ng1 ;) )

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Coming from ng1

• Forget everything that you think you know

• No more controllers, services, factories, providers

• No digest loop (no $scope.$apply() at least)

• No $scope at all ;)

• Still having directives though. Much easier to deal with.

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Hello world

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• https://embed.plnkr.co/?show=preview&show=app%2Fapp.component.ts

• https://angular.io/docs/ts/latest/quickstart.html

Same functionality in ES5

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Data Binding

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https://plnkr.co/edit/RtrRej?p=preview http://blog.thoughtram.io/angular/2016/10/13/two-way-data-binding-in-angular-2.html

Data Binding

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Dependency Injection

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Component lifecycle

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Components interaction• Shared service (hello ng1 ;) )

• @Input/@Output

• ngOnChanges(changes: {[propKey: string]: SimpleChange})

• We can place a local variable on the tag representing the child component<button (click)="timer.start()">Start</button>

<countdown-timer #timer> </countdown-timer>

• Obtain a link to a child component using @ViewChild:

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https://angular.io/docs/ts/latest/cookbook/component-communication.html

RxJS• Reactive Programming

• Implements https://github.com/tc39/proposal-observable

• The Observable type can be used to model push-based data sources such as DOM events, timer intervals, and sockets.

• Observables can be composed with higher-order combinators.

• Observables do not start emitting data until an observer has subscribed.

• ...is a set of libraries to compose asynchronous and event-based programs using observable collections and Array#extras style composition in JavaScript

• Observables + Operators + Schedulers

• Can wrap promises, observables, events and provides exception handling and cancellation

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https://www.youtube.com/watch?v=R4sTvHXkToQ you might have seen it already https://www.youtube.com/watch?v=KOOT7BArVHQ RxJS In-Depth @ AngularConnect

You’ve seen it already

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Simple example

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Consider a task

• Given input textbox and api (GET /items?<term>)

• Call it upon user’s input

• Display results

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Sounds too easy?

How about this?

1. Don’t hit the search endpoint on every key stroke

2. Don’t hit the search endpoint with the same query paramsfor subsequent requests

3. Deal with out-of-order responses

4. Cancel requests when they are not needed

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Change Detection

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Let’s take a look back

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http://blog.mgechev.com/2016/08/14/ahead-of-time-compilation-angular-offline-precompilation/

Zone.JS

• Execution context

• State changes

• Events (click, change, submit…)

• XMLHttpRequests

• Timers (setTimeout, setInterval)

• Monkey-patching on globalScope (Zone.setTimeout)

• No $digest / $apply

• https://www.youtube.com/watch?v=3IqtmUscE_U - good talk about Zones

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Change detection

• https://vsavkin.com/change-detection-in-angular-2-4f216b855d4c#.yd0nbcphd

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Change detection

• https://vsavkin.com/change-detection-in-angular-2-4f216b855d4c#.yd0nbcphd

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NG2 Compiler

• Generated ViewClasses (no need to parse views all the time)

• Inline class properties (google for Hidden Classes)

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Use immutable objects

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• https://vsavkin.com/change-detection-in-angular-2-4f216b855d4c#.yd0nbcphd

JIT Pipeline

1. Write some TypeScript

2. Compile it

3. Bundle

4. Minify

5. Deploy

1. Download application

2. Bootstrap application

3. Compile / generate each view

4. Render application

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AOT Pipeline

1. Write some TypeScript

2. Compile templates -> generate TypeScript code

3. Compile TypeScript to JavaScript

4. Bundle

5. Minify

6. Deploy

1. Download application

2. Bootstrap application

3. Render application

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Why even bother?• Faster page load

• Bundle size

• Strongly-typed ViewClasses

• Can take the best of Google Closure Compiler

• https://w3c.github.io/webappsec-csp/ Content Security Policy

• Energy efficiency

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JIT AOT

Routing

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https://vsavkin.com/angular-2-router-d9e30599f9ea#.gyrajhshr

Dependencies

• Core -> Zone.js, Reflect-Metadata, Observables, Promises

• Promises -> native / shims (es6-shim)

• Observables-> RxJS

• Modules -> Module builder / loader (SystemJS, Browserify, Webpack 1/2)

• AOT -> Typescript, ES2015 modules (no commonjs, no webpack 1.0)

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References:

• https://angular.io/

• https://github.com/mgechev/angular-seed - Modular starter project for Angular 2 with statically typed build and AoT compilation

• https://vsavkin.com/ - site full of useful articles on the topic

• https://leanpub.com/router – a book on Angular 2 router

• http://blog.thoughtram.io/angular/2016/01/06/taking-advantage-of-observables-in-angular2.html - more on observables example

• http://blog.mgechev.com/2016/08/14/ahead-of-time-compilation-angular-offline-precompilation/ ahead-of-time compilation

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Q & A