title: ng-bootstrap dropup and dropdown placement in the same page
body: <p>Is there any option in ng-bootstrap for dropdown and dropup on the same page?
  <br> <br>
  I have tried the below code as given in the <a href="https://ng-bootstrap.github.io/#/components/dropdown/examples#config" rel="nofollow noreferrer">documentation</a> of ng-bootstrap. but it is a Global configuration of dropdowns. <strong>I want dropdown and dropup on the same page</strong>. I'm working with Angular 8.</p>
  
  <pre><code>import {Component} from '@angular/core';
  import {NgbDropdownConfig} from '@ng-bootstrap/ng-bootstrap';
  
  @Component({
    selector: 'ngbd-dropdown-config',
    templateUrl: './dropdown-config.html',
    providers: [NgbDropdownConfig] // add NgbDropdownConfig to the component providers
  })
  export class NgbdDropdownConfig {
    constructor(config: NgbDropdownConfig) {
      // customize default values of dropdowns used by this component tree
      config.placement = 'top-left';
      config.autoClose = false;
    }
  }
  </code></pre>
  
  <p><br></p>
  
  <pre><code>&lt;div ngbDropdown&gt;
      &lt;button class="btn btn-secondary" type="button" id="dropDownMenuButton" ngbDropdownToggle&gt;
        Dropup Menu
      &lt;/button&gt;
      &lt;div class="dropdown-menu tx-13" ngbDropdownMenu aria-labelledby="dropDownMenuButton"&gt;
        &lt;a class="dropdown-item" href="#"&gt;Action&lt;/a&gt;
        &lt;a class="dropdown-item" href="#"&gt;Another action&lt;/a&gt;
        &lt;a class="dropdown-item" href="#"&gt;Something else here&lt;/a&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  
    &lt;div class="dropup" ngbDropdown&gt;
      &lt;button class="btn btn-secondary" type="button" id="dropupMenuButton" ngbDropdownToggle&gt;
        Dropup Menu
      &lt;/button&gt;
      &lt;div class="dropdown-menu tx-13" ngbDropdownMenu aria-labelledby="dropupMenuButton"&gt;
        &lt;a class="dropdown-item" href="#"&gt;Action&lt;/a&gt;
        &lt;a class="dropdown-item" href="#"&gt;Another action&lt;/a&gt;
        &lt;a class="dropdown-item" href="#"&gt;Something else here&lt;/a&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  </code></pre>