Angular ResizeObserver

<!DOCTYPE html>
<html>

  <head>
    <base href="." />
    <script type="text/javascript" charset="utf-8">
      window.AngularVersionForThisPlunker = 'latest'
    </script>
    <title>angular playground</title>
    <link rel="stylesheet" href="style.css" />
    <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script>
    <script src="https://unpkg.com/zone.js/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js/dist/long-stack-trace-zone.js"></script>
    <script src="https://unpkg.com/reflect-metadata@0.1.3/Reflect.js"></script>
    <script src="https://unpkg.com/systemjs@0.19.31/dist/system.js"></script>
    <script src="config.js"></script>
    <script>
    System.import('app')
      .catch(console.error.bind(console));
  </script>
  </head>

  <body>
    <my-app>
    loading...
  </my-app>
  </body>

</html>

/* Styles go here */

input {
  width: 300px;
  border: 2px solid trasnparent;
}

input.ng-invalid {
  border: 2px solid red;
}

### Angular Starter Plunker - Typescript

var angularVersion = '4.3.0';
if(window.AngularVersionForThisPlunker === 'latest'){
  angularVersion = ''; //picks up latest
}
else {
  angularVersion = '@' + window.AngularVersionForThisPlunker;
}

System.config({
  //use typescript for compilation
  transpiler: 'typescript',
  //typescript compiler options
  typescriptOptions: {
    emitDecoratorMetadata: true
  },
  paths: {
    'npm:': 'https://unpkg.com/'
  },
  //map tells the System loader where to look for things
  map: {
    
    'app': './src',
    '@angular/core': 'npm:@angular/core'+ angularVersion + '/bundles/core.umd.js',
    '@angular/common': 'npm:@angular/common' + angularVersion + '/bundles/common.umd.js',
    '@angular/compiler': 'npm:@angular/compiler' + angularVersion  + '/bundles/compiler.umd.js',
    '@angular/platform-browser': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser.umd.js',
    '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic' + angularVersion + '/bundles/platform-browser-dynamic.umd.js',
    '@angular/http': 'npm:@angular/http' + angularVersion + '/bundles/http.umd.js',
    '@angular/router': 'npm:@angular/router' + angularVersion +'/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms' + angularVersion + '/bundles/forms.umd.js',
    '@angular/animations': 'npm:@angular/animations' + angularVersion + '/bundles/animations.umd.js',
    '@angular/platform-browser/animations': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser-animations.umd.js',
    '@angular/animations/browser': 'npm:@angular/animations' + angularVersion + '/bundles/animations-browser.umd.js',
    
    '@angular/core/testing': 'npm:@angular/core' + angularVersion + '/bundles/core-testing.umd.js',
    '@angular/common/testing': 'npm:@angular/common' + angularVersion + '/bundles/common-testing.umd.js',
    '@angular/compiler/testing': 'npm:@angular/compiler' + angularVersion + '/bundles/compiler-testing.umd.js',
    '@angular/platform-browser/testing': 'npm:@angular/platform-browser' + angularVersion + '/bundles/platform-browser-testing.umd.js',
    '@angular/platform-browser-dynamic/testing': 'npm:@angular/platform-browser-dynamic' + angularVersion + '/bundles/platform-browser-dynamic-testing.umd.js',
    '@angular/http/testing': 'npm:@angular/http' + angularVersion + '/bundles/http-testing.umd.js',
    '@angular/router/testing': 'npm:@angular/router' + angularVersion + '/bundles/router-testing.umd.js',
    'tslib': 'npm:tslib@1.6.1',
    'rxjs': 'npm:rxjs',
    'typescript': 'npm:typescript@2.2.1/lib/typescript.js',
    'resize-observer-polyfill': 'npm:resize-observer-polyfill'
  },
  //packages defines our app package
  packages: {
    app: {
      main: './main.ts',
      defaultExtension: 'ts'
    },
    rxjs: {
      defaultExtension: 'js'
    }
  }
});

//main entry point
import {platformBrowserDynamic} from '@angular/platform-browser-dynamic';
import {AppModule} from './app.module';

platformBrowserDynamic().bootstrapModule(AppModule)

//our root app component
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser'
import { FormsModule } from '@angular/forms';
import { CommonModule } from '@angular/common';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';

import { App } from './app.component';
import { ResizeObserverDirective } from './resize-observer.directive';

@NgModule({
  imports: [CommonModule, BrowserModule, FormsModule, BrowserAnimationsModule],
  declarations: [App, ResizeObserverDirective],
  bootstrap: [App]
})
export class AppModule {}

//our root app component
import { Component, ElementRef } from '@angular/core';

@Component({
  selector: 'my-app',
  styleUrls: ['src/app.component.scss'],
  templateUrl: 'src/app.component.html',
})
export class App { 
  name = 'world';
  
  constructor(private el: ElementRef) {
  }
  
  onResize(ev) {
    const width = window.innerWidth;
    const height = window.innerHeight;
    const color = `rgb(${Math.floor(ev.contentRect.width / width * 255)},${Math.floor(ev.contentRect.height / height * 255)},${Math.floor(width / 1000 * 255)})`;
    ev.target.style.backgroundColor = color;
    ev.target.style.borderRadius = `${ev.contentRect.width / 1000 * 200}%`;
  }
}

.resizable {
  border: 1px solid red;
  resize: both;
  overflow: auto;
  min-height: 100px;
  min-width: 100px;
  max-width: 100%;
}

.inner {
  border: 1px solid blue;
  height: 100%;
  width: 100%;
  border-radius: 50%;
}

<div class="resizable" (click)="1">
  <div class="inner" resizeObserver (resize)="onResize($event)" [debounce]="0">
    
  </div>
</div>

import { Directive, ElementRef, EventEmitter, Output, Input, OnDestroy } from '@angular/core';
import ResizeObserver from 'resize-observer-polyfill';

console.log(ResizeObserver);

const entriesMap = new WeakMap();

const ro = new ResizeObserver(entries => {
  for (const entry of entries) {
    if (entriesMap.has(entry.target)) {
      const comp = entriesMap.get(entry.target);
      comp._resizeCallback(entry);
    }
  }
});

@Directive({ selector: '[resizeObserver]' })
export class ResizeObserverDirective implements OnDestroy {
  @Output()
  resize = new EventEmitter();
  
  @Input()
  get debounce() {
    return this._debounce;
  }
  
  set debounce(val) {
    if (this._debounce !== val) {
      this._debounce = val;
      this._resizeCallback = debounce(entry => this.resize.emit(entry), this._debounce);
    }
  }
  
  _debounce = 0;
  _resizeCallback: any;
  
  constructor(private el: ElementRef) {
    const target = this.el.nativeElement;
    entriesMap.set(target, this);
    ro.observe(target);
  }
  
  _resizeCallback(entry) {
    this.resize.emit(entry);
  }
  
  ngOnDestroy() {
    const target = this.el.nativeElement;
    ro.unobserve(target);
    entriesMap.delete(target);
  }
}

function debounce(func, wait, immediate) {
	var timeout;
	return function() {
		var context = this, args = arguments;
		var later = function() {
			timeout = null;
			if (!immediate) func.apply(context, args);
		};
		var callNow = immediate && !timeout;
		clearTimeout(timeout);
		timeout = setTimeout(later, wait);
		if (callNow) func.apply(context, args);
	};
};