Example usage of the collapse 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/core-js@^2.4.1/client/shim.js"></script>
    <script src="https://unpkg.com/zone.js@0.8.10/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js@0.8.10/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: '4.0.3'
  };
  
  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.ng + '/bundles/router.umd.js',
    '@angular/forms': 'npm:@angular/forms@' + ver.ng + '/bundles/forms.umd.js',

    'rxjs': 'npm:rxjs@^5.0.1',
    'typescript': 'npm:typescript@2.1.5/lib/typescript.js',

    '@ng-bootstrap/ng-bootstrap': 'npm:@ng-bootstrap/ng-bootstrap@1.0.0-alpha.29/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 { NgbdCollapseBasic } from './collapse-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-collapse-basic></ngbd-collapse-basic>
  </div>
  `
})
export class App {
}   

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

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

@Component({
  selector: 'ngbd-collapse-basic',
  templateUrl: 'src/collapse-basic.html',
  styles: [`
  
  
  `]
})
export class NgbdCollapseBasic {
  public isCollapsed = true;
}

<ul class="nav nav-pills">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>

<li class="nav-item dropdown">
  <a class="nav-link dropdown-toggle" (click)="isCollapsed = !isCollapsed"
          [attr.aria-expanded]="!isCollapsed" aria-controls="collapseExample">
    Toggle
  </a>
  <div class="dropdown-menu p-3" id="collapseExample" [ngbCollapse]="isCollapsed">
        <form>
            <div class="form-group">
                <label for="exampleInputEmail1">Email address</label>
                <input type="email" class="form-control" id="exampleInputEmail1" placeholder="Email">
            </div>
            <div class="form-group">
                <label for="exampleInputPassword1">Password</label>
                <input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
            </div>
            <div class="form-group">
                <label for="exampleInputFile">File input</label>
                <input type="file" id="exampleInputFile">
                <p class="help-block">Example block-level help text here.</p>
            </div>
            <div class="checkbox">
                <label>
                <input type="checkbox"> Check me out
                </label>
            </div>
            <button type="submit" class="btn btn-default">Submit</button>
        </form>
    </div>
</li>
</ul>