SO: 42170566 - ngbDropdown Example usage of the dropdown widget from https://ng-bootstrap.github.io

<!DOCTYPE html>
<html>

  <head>
  <base href="." />
    <title>ng-bootstrap demo</title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.6/css/bootstrap.min.css" />
    <script src="https://unpkg.com/zone.js@^0.7.2/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js@^0.7.2/dist/long-stack-trace-zone.js"></script>
    <script src="https://unpkg.com/reflect-metadata@^0.1.8/Reflect.js"></script>
    <script src="https://unpkg.com/systemjs@^0.19.40/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>

var ver = {
    ng: '2.3.1',
    ngRouter: '3.3.1'
  };
  
  System.config({
  //use typescript for compilation
  transpiler: 'typescript',
  //typescript compiler options
  typescriptOptions: {
    emitDecoratorMetadata: true
  },
  paths: {
    'npm:': 'https://unpkg.com/'
  },
  map: {

    'app': './src',

    '@angular/core': 'npm:@angular/core@' + ver.ng + '/bundles/core.umd.js',
    '@angular/common': 'npm:@angular/common@' + ver.ng + '/bundles/common.umd.js',
    '@angular/compiler': 'npm:@angular/compiler@' + ver.ng + '/bundles/compiler.umd.js',
    '@angular/platform-browser': 'npm:@angular/platform-browser@' + ver.ng + '/bundles/platform-browser.umd.js',
    '@angular/platform-browser-dynamic': 'npm:@angular/platform-browser-dynamic@' + ver.ng + '/bundles/platform-browser-dynamic.umd.js',
    '@angular/http': 'npm:@angular/http@' + ver.ng + '/bundles/http.umd.js',
    '@angular/router': 'npm:@angular/router@' + ver.ngRouter + '/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms@' + ver.ng + '/bundles/forms.umd.js',

    'rxjs': 'npm:rxjs@5.0.0-rc.4',
    'typescript': 'npm:typescript@2.0.10/lib/typescript.js',

    '@ng-bootstrap/ng-bootstrap': 'npm:@ng-bootstrap/ng-bootstrap@1.0.0-alpha.20/bundles/ng-bootstrap.js'
  },
  packages: {
    app: {
      main: './main.ts',
      defaultExtension: 'ts'
    },
    rxjs: {
      defaultExtension: 'js'
    }
  }
});

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

platformBrowserDynamic().bootstrapModule(AppModule);


import { Component, NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { JsonpModule } from '@angular/http';
import { NgbModule } from '@ng-bootstrap/ng-bootstrap';
import { NgbdDropdownBasic } from './dropdown-basic';

@Component({
  selector: 'my-app',
  template: `
    <div class="container-fluid">
    
    <hr>
    <p>
      This is a demo plnkr forked from the <strong>ng-bootstrap</strong> project: Angular powered Bootstrap.
      Visit <a href="https://ng-bootstrap.github.io/" target="_blank">https://ng-bootstrap.github.io</a> for more widgets and demos.
    </p>
    <hr>

    <ngbd-dropdown-basic></ngbd-dropdown-basic>
  </div>
  `
})
export class App {
}   

@NgModule({
  imports: [BrowserModule, FormsModule, ReactiveFormsModule, JsonpModule, NgbModule.forRoot()], 
  declarations: [App, NgbdDropdownBasic]
  bootstrap: [App]
}) 
export class AppModule {}

import {Component} from '@angular/core';

@Component({
  selector: 'ngbd-dropdown-basic',
  templateUrl: 'src/dropdown-basic.html'
})
export class NgbdDropdownBasic {

  sortOrders: string[] = ["Year", "Title", "Author"];
  selectedSortOrder: string = "Sort by...";
  
  ChangeSortOrder(newSortOrder: string) { 
    this.selectedSortOrder = newSortOrder;
  }

}

<div ngbDropdown class="d-inline-block">
  <button class="btn btn-outline-primary" id="sortMenu" ngbDropdownToggle>{{selectedSortOrder}}</button>
  <div class="dropdown-menu" aria-labelledby="sortMenu">
    <button class="dropdown-item" *ngFor="let sortOrder of sortOrders" (click)="ChangeSortOrder(sortOrder)" >{{sortOrder}}</button>
  </div>
</div>