The Many Meanings
of IoC in JavaScript

Tomasz Ducin

Tomasz Ducin

21.10.2019, Katowice

The Many Meanings
of IoC in JavaScript

Tomasz Ducin

16.11.2018, Warsaw

The Many Meanings of IoC in JavaScript

Software Consultant & Architect

Trainer, Speaker, JS/TS Expert

Warsaw, PL

Hi, I'm Tomasz

ducin.it

@tomasz_ducin

Tomasz Ducin

developer & architect

trainer @Bottega IT Minds

consultant

Title Text

INVERSION
OF CONTROL

INVERSION
OF CONTROL

INVERSION
OF
CONTROL

taxi.takeMeTo(hotel);

LOSING CONTROL

🤔 MEDIATOR?
🤔 PUB-SUB?

🤔 MEDIATOR?
🤔 PUB-SUB?

IMPERATIVE

VS

DECLARATIVE

(NOT ONLY)
DEPENDENCY
INJECTION

(NOT ONLY)
DEPENDENCY
INJECTION

import { Component } from '@angular/core';
import { MyService } from './my-service';

@Component({
  selector: 'my-component',
  template: ...
})
export class MyComponent {
  constructor(myService: MyService) {}
  ...
}
import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root',
})
export class MyService {
  ...
}
class CoffeeMaker {

    constructor(container) {
        this.beanFactory = container.get(BeanFactory);
        this.sugarFactory = container.get(SugarFactory);
        this.waterFactory = container.get(WaterFactory);
    }

    make() {
        this.beanFactory.create();
        this.sugarFactory.create();
        this.waterFactory.create();
    }

}

var Container = require("typedi").Container;
var coffeeMaker = Container.get(CoffeeMaker);
coffeeMaker.make();
class CoffeeMaker {

    constructor(container) {
        this.beanFactory = container.get(BeanFactory);
        this.sugarFactory = container.get(SugarFactory);
        this.waterFactory = container.get(WaterFactory);
    }

    make() {
        this.beanFactory.create();
        this.sugarFactory.create();
        this.waterFactory.create();
    }

}

var Container = require("typedi").Container;
var coffeeMaker = Container.get(CoffeeMaker);
coffeeMaker.make();

DEPENDENCY INJECTION

SERVICE LOCATOR

REDUX

(READ)

(WRITE)

PULL

VS

PUSH

pull vs push

Redux store API:

  • store.dispatch(action)
  • store.getState() - pull-based
  • store.subscribe(listener) - push-based

TELL, DON'T ASK
(OOP PRINCIPLE)

getState()
dispatch()
subscribe()

🤨

PRINCIPLE

PUB-SUB

REACT

REACTIVE

VIEW

UPDATES

const Employee = ({ employee }) => (<div>
  <span>{ employee.firstName }</span>
  <span>{ employee.lastName }</span>
  <span>{ employee.age}</span>
</div>)
class SomeService extends React.Component {
  performSomeLogic(){
    // including state mgmt, webservices, session 
  }

  render(){ // should have NO view
    return this.props.render(this.state)
  }
}



const Page = () => <div>
  <SomeService render={svcState =>
    <>
      <h1>{ svcState.header }</h1>
      <p>{ svcState.content }</p>
    </>
  }></SomeService>
</div>

RENDER PROPS:
IoC INSIDE IoC

RxJS

REACTIVE

STREAMS

let rate = 3.94;
let amount = 1000;
let exchange = amount / rate; // 253.80

rate = 3.97;
exchange // DESYNC, sync manually!
let rate$ = 3.94;
let amount$ = 1000;
let exchange$ = amount$ / rate$; // 253.80

rate$ = 3.97;
exchange$ // 251.89

slightly simplified

let rate$ = fromEvent(...) // WebSocket, 3.94 
let amount$ = fromEvent(...) // input, 1000
let exchange$ = combineLatest(amount$, rate$,
    (amount, rate) => amount / rate)
// AUTO -> 253.80

rate$ // external -> 3.97
exchange$ // AUTO -> 251.89

RX

REDEFINES

WHAT A VARIABLE IS

WHAT'S NEXT?

  • no Virtual DOM

  • true reactivity

<script>
  const price = 9.99
  let quantity = 0;
  $: totalPrice = quantity * price;

  function handleClick() {
    quantity += 1;
  }
</script>

Svelte

THANK YOU!

The many meanings of IoC in JavaScript

By Tomasz Ducin

The many meanings of IoC in JavaScript

  • 310
Loading comments...

More from Tomasz Ducin