Example usage of the typeahead 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@^0.6.23/dist/zone.js"></script>
    <script src="https://unpkg.com/zone.js@^0.6.23/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: '2.0.0',
    ngRouter: '3.0.0'
  };
  
  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-beta.12',
    'typescript': 'npm:typescript@2.0.10/lib/typescript.js',

    '@ng-bootstrap/ng-bootstrap': 'npm:@ng-bootstrap/ng-bootstrap@1.0.0-alpha.18/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 { NgbdTypeaheadTemplate } from './typeahead-template';

@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 2 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-typeahead-template></ngbd-typeahead-template>
  </div>
  `
})
export class App {
}   

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

import {Component} from '@angular/core';
import {Observable} from 'rxjs/Observable';
import {Subject} from 'rxjs/Subject';
import 'rxjs/add/operator/debounceTime';
import 'rxjs/add/operator/map';
import 'rxjs/add/operator/merge';

const statesWithFlags = [
  {'name': 'Alabama', 'flag': '5/5c/Flag_of_Alabama.svg/45px-Flag_of_Alabama.svg.png'},
  {'name': 'Alaska', 'flag': 'e/e6/Flag_of_Alaska.svg/43px-Flag_of_Alaska.svg.png'},
  {'name': 'Arizona', 'flag': '9/9d/Flag_of_Arizona.svg/45px-Flag_of_Arizona.svg.png'},
  {'name': 'Arkansas', 'flag': '9/9d/Flag_of_Arkansas.svg/45px-Flag_of_Arkansas.svg.png'},
  {'name': 'California', 'flag': '0/01/Flag_of_California.svg/45px-Flag_of_California.svg.png'},
  {'name': 'Colorado', 'flag': '4/46/Flag_of_Colorado.svg/45px-Flag_of_Colorado.svg.png'},
  {'name': 'Connecticut', 'flag': '9/96/Flag_of_Connecticut.svg/39px-Flag_of_Connecticut.svg.png'},
  {'name': 'Delaware', 'flag': 'c/c6/Flag_of_Delaware.svg/45px-Flag_of_Delaware.svg.png'},
  {'name': 'Florida', 'flag': 'f/f7/Flag_of_Florida.svg/45px-Flag_of_Florida.svg.png'},
  {'name': 'Georgia', 'flag': '5/54/Flag_of_Georgia_%28U.S._state%29.svg/46px-Flag_of_Georgia_%28U.S._state%29.svg.png'},
  {'name': 'Hawaii', 'flag': 'e/ef/Flag_of_Hawaii.svg/46px-Flag_of_Hawaii.svg.png'},
  {'name': 'Idaho', 'flag': 'a/a4/Flag_of_Idaho.svg/38px-Flag_of_Idaho.svg.png'},
  {'name': 'Illinois', 'flag': '0/01/Flag_of_Illinois.svg/46px-Flag_of_Illinois.svg.png'},
  {'name': 'Indiana', 'flag': 'a/ac/Flag_of_Indiana.svg/45px-Flag_of_Indiana.svg.png'},
  {'name': 'Iowa', 'flag': 'a/aa/Flag_of_Iowa.svg/44px-Flag_of_Iowa.svg.png'},
  {'name': 'Kansas', 'flag': 'd/da/Flag_of_Kansas.svg/46px-Flag_of_Kansas.svg.png'},
  {'name': 'Kentucky', 'flag': '8/8d/Flag_of_Kentucky.svg/46px-Flag_of_Kentucky.svg.png'},
  {'name': 'Louisiana', 'flag': 'e/e0/Flag_of_Louisiana.svg/46px-Flag_of_Louisiana.svg.png'},
  {'name': 'Maine', 'flag': '3/35/Flag_of_Maine.svg/45px-Flag_of_Maine.svg.png'},
  {'name': 'Maryland', 'flag': 'a/a0/Flag_of_Maryland.svg/45px-Flag_of_Maryland.svg.png'},
  {'name': 'Massachusetts', 'flag': 'f/f2/Flag_of_Massachusetts.svg/46px-Flag_of_Massachusetts.svg.png'},
  {'name': 'Michigan', 'flag': 'b/b5/Flag_of_Michigan.svg/45px-Flag_of_Michigan.svg.png'},
  {'name': 'Minnesota', 'flag': 'b/b9/Flag_of_Minnesota.svg/46px-Flag_of_Minnesota.svg.png'},
  {'name': 'Mississippi', 'flag': '4/42/Flag_of_Mississippi.svg/45px-Flag_of_Mississippi.svg.png'},
  {'name': 'Missouri', 'flag': '5/5a/Flag_of_Missouri.svg/46px-Flag_of_Missouri.svg.png'},
  {'name': 'Montana', 'flag': 'c/cb/Flag_of_Montana.svg/45px-Flag_of_Montana.svg.png'},
  {'name': 'Nebraska', 'flag': '4/4d/Flag_of_Nebraska.svg/46px-Flag_of_Nebraska.svg.png'},
  {'name': 'Nevada', 'flag': 'f/f1/Flag_of_Nevada.svg/45px-Flag_of_Nevada.svg.png'},
  {'name': 'New Hampshire', 'flag': '2/28/Flag_of_New_Hampshire.svg/45px-Flag_of_New_Hampshire.svg.png'},
  {'name': 'New Jersey', 'flag': '9/92/Flag_of_New_Jersey.svg/45px-Flag_of_New_Jersey.svg.png'},
  {'name': 'New Mexico', 'flag': 'c/c3/Flag_of_New_Mexico.svg/45px-Flag_of_New_Mexico.svg.png'},
  {'name': 'New York', 'flag': '1/1a/Flag_of_New_York.svg/46px-Flag_of_New_York.svg.png'},
  {'name': 'North Carolina', 'flag': 'b/bb/Flag_of_North_Carolina.svg/45px-Flag_of_North_Carolina.svg.png'},
  {'name': 'North Dakota', 'flag': 'e/ee/Flag_of_North_Dakota.svg/38px-Flag_of_North_Dakota.svg.png'},
  {'name': 'Ohio', 'flag': '4/4c/Flag_of_Ohio.svg/46px-Flag_of_Ohio.svg.png'},
  {'name': 'Oklahoma', 'flag': '6/6e/Flag_of_Oklahoma.svg/45px-Flag_of_Oklahoma.svg.png'},
  {'name': 'Oregon', 'flag': 'b/b9/Flag_of_Oregon.svg/46px-Flag_of_Oregon.svg.png'},
  {'name': 'Pennsylvania', 'flag': 'f/f7/Flag_of_Pennsylvania.svg/45px-Flag_of_Pennsylvania.svg.png'},
  {'name': 'Rhode Island', 'flag': 'f/f3/Flag_of_Rhode_Island.svg/32px-Flag_of_Rhode_Island.svg.png'},
  {'name': 'South Carolina', 'flag': '6/69/Flag_of_South_Carolina.svg/45px-Flag_of_South_Carolina.svg.png'},
  {'name': 'South Dakota', 'flag': '1/1a/Flag_of_South_Dakota.svg/46px-Flag_of_South_Dakota.svg.png'},
  {'name': 'Tennessee', 'flag': '9/9e/Flag_of_Tennessee.svg/46px-Flag_of_Tennessee.svg.png'},
  {'name': 'Texas', 'flag': 'f/f7/Flag_of_Texas.svg/45px-Flag_of_Texas.svg.png'},
  {'name': 'Utah', 'flag': 'f/f6/Flag_of_Utah.svg/45px-Flag_of_Utah.svg.png'},
  {'name': 'Vermont', 'flag': '4/49/Flag_of_Vermont.svg/46px-Flag_of_Vermont.svg.png'},
  {'name': 'Virginia', 'flag': '4/47/Flag_of_Virginia.svg/44px-Flag_of_Virginia.svg.png'},
  {'name': 'Washington', 'flag': '5/54/Flag_of_Washington.svg/46px-Flag_of_Washington.svg.png'},
  {'name': 'West Virginia', 'flag': '2/22/Flag_of_West_Virginia.svg/46px-Flag_of_West_Virginia.svg.png'},
  {'name': 'Wisconsin', 'flag': '2/22/Flag_of_Wisconsin.svg/45px-Flag_of_Wisconsin.svg.png'},
  {'name': 'Wyoming', 'flag': 'b/bc/Flag_of_Wyoming.svg/43px-Flag_of_Wyoming.svg.png'}
];

@Component({
  selector: 'ngbd-typeahead-template',
  templateUrl: 'src/typeahead-template.html',
  styles: [`.form-control { width: 300px; }`]
})
export class NgbdTypeaheadTemplate {
  public model: any;
  
  private resultOptionsSubject: Subject<any> = new Subject<any>();
  
  private jsCode:string=`... line 159 ->
  .let(this.ngbTypeahead)
            .do(function (_) {
              if(this._userInput==null){
                _this._userInput=this._elementRef.nativeElement.value;
              };
              ...`
  
  constructor(){
     
  }

  search = (text$: Observable<string>) =>
    this.resultOptionsSubject.merge(text$.debounceTime(200).map(t=>{return {term:t}}))
      
      .map(termObj =>{
       if(termObj.showAll){
         return statesWithFlags.slice();
       }
       if(termObj.term){
         return statesWithFlags.filter(v => new RegExp(termObj.term, 'gi').test(v.name)).slice(0, 10)
       }
       return [];
        });

  formatter = (x: {name: string}) => x.name;
  
  showAll(ev){
    ev.stopPropagation();
    this.resultOptionsSubject.next({showAll:true})
  }
  
}

<p>A typeahead example that uses custom template for results display and uses object as a model</p>

<h5>1) click on 'show all'</h5>
<h5>2) click outside of dropdown so popup is closed and no value selected</h5>
<h5>3) as popup was not opened through input change event 'undefined' gets populated because in NgbTypeahead.prototype.dismissPopup()  this._userInput is 'undefined'</h5>
<h5>Posible solution: NgbTypeahead._writeInputValue (line 275) should have value!=null check</h5>
<h5>also set _userInput to input value if popup is not displayed from input event</h5>
<code>{{jsCode}}
              </code>
<br>
<template #rt let-r="result" let-t="term">
  <img [src]="'https://upload.wikimedia.org/wikipedia/commons/thumb/' + r.flag" width="16">
  {{ r.name}}
</template>
<a href="" (click)="!!showAll($event)">show all</a>
<input type="text" class="form-control" [(ngModel)]="model" [ngbTypeahead]="search" [resultTemplate]="rt" [inputFormatter]="formatter" />
<hr>
<pre>Model: {{ model | json }}</pre>