Numbers only - Custom input

<!DOCTYPE html>
<html>

  <head>
    <base href="." />
    <title>angular playground</title>
    <link rel="stylesheet" href="style.css" />
    <script type="text/javascript" charset="utf-8">
      window.window.AngularVersionForThisPlunker = '4.2.6'
    </script>
    <script src="https://unpkg.com/core-js@2.4.1/client/shim.min.js"></script>
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    <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 */

### Angular Starter Plunker - Typescript

var angularVersion;
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',
    
    'rxjs': 'npm:rxjs@5.4.2',
    'typescript': 'npm:typescript@2.2.1/lib/typescript.js'
  },
  //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';

platformBrowserDynamic().bootstrapModule(AppModule)

//our root app component
import {Component, NgModule, VERSION} from '@angular/core'
import {BrowserModule} from '@angular/platform-browser'
import { CustomInputComponent } from './custom-input.ts';
import { FormsModule } from '@angular/forms';

@Component({
  selector: 'my-app',
  template: `
    <form #demoForm="ngForm">
          <custom-input name="someValue" 
                          [(ngModel)]="value">
             <div>This div will be placed instead ng-content</div>
          </custom-input>
        </form>
  `,
})
export class App {
  value:string = '';
  constructor() {
  }
}

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

import { Component, forwardRef,Renderer2, 
  Injector, ElementRef } from '@angular/core';
import { NG_VALUE_ACCESSOR, ControlValueAccessor, NgControl } from '@angular/forms';

const noop = () => {
};

export const CUSTOM_INPUT_CONTROL_VALUE_ACCESSOR: any = {
    provide: NG_VALUE_ACCESSOR,
    useExisting: forwardRef(() => CustomInputComponent),
    multi: true
};

@Component({
    selector: 'custom-input',
    template: `<div class="form-group">
                    <label><ng-content></ng-content>
                        <input  (input)="handleInput($event.target)" 
                                (blur)="onBlur()" >
                    </label>
                </div>`,
    providers: [CUSTOM_INPUT_CONTROL_VALUE_ACCESSOR]
})
export class CustomInputComponent implements ControlValueAccessor {

constructor(
    private _renderer: Renderer2, 
    private _elementRef: ElementRef, 
    private _inj: Injector) {
  }
  
    //Placeholders for the callbacks which are later provided
    //by the Control Value Accessor
    private onTouchedCallback: () => void = noop;
    private onChangeCallback: (_: any) => void = noop;

    //Set touched on blur
    onBlur() {
        this.onTouchedCallback();
    }

    //Write value to ngModel
    writeValue(value: any) {
       const normalizedValue = value == null ? '' : value;
       this._renderer.setProperty(this._elementRef.nativeElement, 'value', normalizedValue);
    }

    //From ControlValueAccessor interface
    registerOnChange(fn: any) {
        this.onChangeCallback = fn;
    }

    //From ControlValueAccessor interface
    registerOnTouched(fn: any) {
        this.onTouchedCallback = fn;
    }
    
    handleInput(target: any): void {
      const val = target.value;
      let regexp = new RegExp('\\d+(?:[\.]\\d{0,})?$');
        let isNumber = regexp.test(val);
        let isEmpty = val == '';
        if(!isNumber && !isEmpty) {
          let model = this._inj.get(NgControl);  // get NgModel
          model.control.setValue(model.value);
          target.value = model.value;
          return;
        }

        this.onChangeCallback(val);
   }

}